psql是一个 PostgreSQL的基于终端的前端。 它让你能交互式地键入查询，把它们发送给 PostgreSQL，并且查看查询结果。 或者，输入可以来自于一个文件。此外，它还提供一些元命令和多种类似 shell 的特性来为编写脚本和自动化多种任务提供便利。
把所有非空输入行按照它们被读入的形式打印到标准输出（不适用于交互式行读取）。 这等效于把变量ECHO设置为 all。
切换到非对齐输出模式（默认输出模式是对齐的）。
指定psql执行一个命令字符串（ command）然后退出。 这在 shell 脚本中有用。使用这个选项会忽略开始文件（ psqlrc以及 ~/.psqlrc）。
command必须是 一个服务器完全可解析的命令字符串（即不包含 psql相关的特性）或者单个反斜线命令。 因此不能用这个选项混合SQL和 psql元命令。要那样做，可以把字符串用 管道输送到psql中，例如， echo '\x \\ SELECT * FROM foo;' | psql（ \\是分隔符元命令）。
如果该命令字符串包含多个 SQL 命令，它们会在一个单一事务中 被处理（除非字符串中包括了显式的 BEGIN/COMMIT命令把它分隔 成多个事务）。这和把同样的字符串输送给 psql的标准输入的行为不同。还有， 只有最后一个 SQL 命令的结果会被返回。
由于这些遗留行为，把多于一个命令放在-c 字符串中通常会得到意料之外的结果。最好把多个命令输送给 psql的标准输入，按照上面 所说的使用echo或者通过这里 记录的 shell，例如：
psql <<EOF \x SELECT * FROM foo; EOF
指定要连接的数据库的名称。这等效于指定dbname为命令行上的第一个 非选项参数。
如果这个参数包含一个=符号或者 以一个合法的URI前缀（ postgresql://或者 postgres://）开始，它会被当作一个 conninfo字符串。详见Section 31.1.1。
也把发送到服务器的所有 SQL 命令复制到标准输出。这等效于把变量 ECHO设置为queries。
回显\d以及其他反斜线命令生成的实际查询。 可以用它来学习psql的内部操作。这等效 于把变量ECHO_HIDDEN设置为on。
使用文件filename 作为命令的来源，而不是交互式地读取命令。在文件被处理后， psql会终止。在很多方面，这等效于 元命令\i。
如果filename是- （连字符），那么会读取标准输入。
使用这个选项与psql < filename有细微的不同。 通常，两种形式都可以做到我们所期望的，但是使用 -f启用了一些好的特性，例如带有行号的错误消息。 使用这个选项还有一丝机会可以降低启动开销。在另一方面，使用 shell 输入重定向的变体（理论上）保证会得到与手工输入时相同的输出。
使用separator 作为非对齐输出的域分隔符。这等效于 \pset fieldsep或者\f。
指定运行服务器的机器的主机名。如果这个值由一个斜线开始， 它会被用作 Unix 域套接字的目录。
打开HTML表格输出。这等效于 \pset format html或者 \H命令。
列出所有可用的数据库，然后退出。其他非连接选项会被忽略。 这与元命令\list类似。
除了把所有查询输出写到普通输出目标之外，还写到文件filename中。
不使用Readline做行编辑并且不使用命令 历史。在剪切和粘贴时，关掉 Tab 展开会有所帮助。
把所有查询输出放到文件filename中。这等效于 命令\o。
指定服务器用于监听连接的 TCP 端口或者本地 Unix 域套接字文件扩展。 默认是PGPORT环境变量的值，如果没有设置，则 默认为编译时指定的端口号（通常是5432）。
以\pset的形式指定打印选项。注意，这里 你必须用一个等号而不是空格来分隔名称和值。例如，要设置输出格式 为LaTeX，应该写成 -P format=latex。
指定psql应该安静地工作。默认情况下，它 会打印出欢迎消息以及多种输出。如果使用了这个选项，以上那些就都不会 输出。在使用-c选项时，配合这个选项很有用。这等效 于设置变量QUIET为on。
把separator用作 非对齐输出的记录分隔符。这等效于 \pset recordsep命令。
运行在单步模式中。这意味着在每个命令被发送给服务器之前都会 提示用户一个可以取消执行的选项。使用这个选项可以调试脚本。
运行在单行模式中，其中新行会终止一个 SQL 命令，就像分号的作用一样。
Note: 这种模式被提供给那些坚持使用它的用户，但是并不一定要使用它。特别地， 如果在一行中混合了SQL和元命令，那对于没有 经的用户来说，它们的执行顺序可能不总是那么清晰。
关闭打印列名和结果行计数页脚等。这等效于 \t命令。
指定要替换
HTML table
标签的选项。详见
\pset。
作为用户username而不是默认用户 连接到数据库（当然，你必须具有这样做的权限）。
执行一次变量赋值，和\set元命令相似。 注意你必须在命令行上用等号分隔名字和值（如果有）。要重置一个 变量，去掉等号就行。要把一个变量置为空值，使用等号但是去掉值。 这些赋值都是在启动的很早期阶段完成的，因此为内部目的保留的变 量可能会在后面被覆盖。
打印psql版本并且退出。
从不发出一个口令提示。如果服务器要求口令认证并且没有其他方式提供口令（例如一个.pgpass文件），那儿连接尝试将失败。这个选项对于批处理任务和脚本有用，因为在其中没有一个用户来输入口令。
注意这个选项将对整个会话保持设置，并且因此它会影响元命令 \connect的使用，就像初始的连接尝试那样。
强制psql在连接到一个数据库之前提示要求一个口令。
这个选项不是必不可少的，因为如果服务器要求口令认证，psql将自动提示要求一个口令。但是，psql将浪费一次连接尝试来发现服务器想要一个口令。在某些情况下值得用-W来避免额外的连接尝试。
注意这个选项将对整个会话保持设置，并且因此它会影响元命令 \connect的使用，就像初始的连接尝试那样。
打开扩展表格式模式。这等效于 \x命令。
不读取启动文件（要么是系统范围的 psqlrc文件，要么是用户的 ~/.psqlrc文件）。
设置非对齐输出的域分隔符为零字节。
设置非对齐输出的记录分隔符为零字节。例如，这对与 xargs -0配合有关。
在psql执行脚本时，增加这个选项会在 脚本上包裹BEGIN/COMMIT来让 该脚本在一个事务中执行。这确保了所有命令要么成功完成，要么任何 更改都不被应用。
如果脚本本身使用了BEGIN、COMMIT 或者ROLLBACK，这个选项将不会得到想要的效果。 还有，如果该脚本包含任何不能在一个事务块中执行的命令，指定这个 选项将导致该命令失败（进而导致整个事务失败）。
显示有关psql命令行参数的帮助并且退出。
如果psql正常完成，它会向 shell 返回 0。 如果它自身发生一个致命错误（例如内存用完、找不到文件），它会返回 1。 如果到服务器的连接出问题并且事务不是交互式的，它会返回 2。如果在脚本 中发生错误，它会返回 3 并且变量 ON_ERROR_STOP会被设置。
psql是一个常规 PostgreSQL客户端应用。为了连接到 数据库，你需要知道你的目标数据库的名称、主机名和该服务器的端口号， 还有要作为哪个用户名连接。可以通过命令行选项告知 psql这些参数，分别是-d、 -h、-p以及 -U。如果发现一个参数不属于任何选项，它将被解释为 数据库名称（如果已经给出数据库名称，就解释为用户名）。并非所有这些 选项都是必需的，它们都有可用的默认值。如果省略主机名， psql将通过一个 Unix 域套接字连接到本地主机上的服务器， 或者通过 TCP/IP 连接到没有 Unix 域套接字的主机上的localhost。 默认端口号则在编译时决定。由于数据库服务器使用相同的默认值，大多数情况 下你将不必指定端口。默认的用户名是你的操作系统用户名，它也会是默认的 数据库名。注意你不一定能连接到任意用户名下的任何数据库。你的数据库管 理员应该已经告知过你有关你的访问权限。
当默认值不是很符合实际时，可以把环境变量 PGDATABASE、PGHOST、 PGPORT以及PGUSER 设置为适当的值，这样也能节省一些敲打键盘的工作（额外的环境 变量可见Section 31.14）。用一个 ~/.pgpass文件来避免定期输入密码也很方便。 详见Section 31.15。
另一种指定连接参数的方法是用一个 conninfo字符串或者一个 URI，它可以被用来替代数据库名。这种 机制可以让我们对连接具有很广的控制权。例如：
$ psql "service=myservice sslmode=require" $ psql postgresql://dbmaster:5433/mydb?sslmode=require
用这种方式，你也可以把LDAP用于 Section 31.17中描述的连接参数查找。可用连接选项的 更多信息请见Section 31.1.2。
If the connection could not be made for any reason (e.g., insufficient privileges, server is not running on the targeted host, etc.), psql will return an error and terminate.
If both standard input and standard output are a terminal, then psql sets the client encoding to "auto", which will detect the appropriate client encoding from the locale settings (LC_CTYPE environment variable on Unix systems). If this doesn't work out as expected, the client encoding can be overridden using the environment variable PGCLIENTENCODING.
In normal operation, psql provides a prompt with the name of the database to which psql is currently connected, followed by the string =>. For example:
$ psql testdb psql (9.4.4) Type "help" for help. testdb=>
At the prompt, the user can type in SQL commands. Ordinarily, input lines are sent to the server when a command-terminating semicolon is reached. An end of line does not terminate a command. Thus commands can be spread over several lines for clarity. If the command was sent and executed without error, the results of the command are displayed on the screen.
Whenever a command is executed, psql also polls for asynchronous notification events generated by LISTEN and NOTIFY.
While C-style block comments are passed to the server for processing and removal, SQL-standard comments are removed by psql.
Anything you enter in psql that begins with an unquoted backslash is a psql meta-command that is processed by psql itself. These commands make psql more useful for administration or scripting. Meta-commands are often called slash or backslash commands.
The format of a psql command is the backslash, followed immediately by a command verb, then any arguments. The arguments are separated from the command verb and each other by any number of whitespace characters.
To include whitespace in an argument you can quote it with single quotes. To include a single quote in an argument, write two single quotes within single-quoted text. Anything contained in single quotes is furthermore subject to C-like substitutions for \n (new line), \t (tab), \b (backspace), \r (carriage return), \f (form feed), \digits (octal), and \xdigits (hexadecimal). A backslash preceding any other character within single-quoted text quotes that single character, whatever it is.
Within an argument, text that is enclosed in backquotes (`) is taken as a command line that is passed to the shell. The output of the command (with any trailing newline removed) replaces the backquoted text.
If an unquoted colon (:) followed by a psql variable name appears within an argument, it is replaced by the variable's value, as described in SQL Interpolation.
Some commands take an SQL identifier (such as a table name) as argument. These arguments follow the syntax rules of SQL: Unquoted letters are forced to lowercase, while double quotes (") protect letters from case conversion and allow incorporation of whitespace into the identifier. Within double quotes, paired double quotes reduce to a single double quote in the resulting name. For example, FOO"BAR"BAZ is interpreted as fooBARbaz, and "A weird"" name" becomes A weird" name.
Parsing for arguments stops at the end of the line, or when another unquoted backslash is found. An unquoted backslash is taken as the beginning of a new meta-command. The special sequence \\ (two backslashes) marks the end of arguments and continues parsing SQL commands, if any. That way SQL and psql commands can be freely mixed on a line. But in any case, the arguments of a meta-command cannot continue beyond the end of the line.
The following meta-commands are defined:
If the current table output format is unaligned, it is switched to aligned. If it is not unaligned, it is set to unaligned. This command is kept for backwards compatibility. See \pset for a more general solution.
Establishes a new connection to a PostgreSQL server. The connection parameters to use can be specified either using a positional syntax, or using conninfo connection strings as detailed in Section 31.1.1.
When using positional parameters, if any of dbname, username, host or port are omitted or specified as -, the value of that parameter from the previous connection is used; if there is no previous connection, the libpq default for the parameter's value is used. When using conninfo strings, no values from the previous connection are used for the new connection.
If the new connection is successfully made, the previous connection is closed. If the connection attempt failed (wrong user name, access denied, etc.), the previous connection will only be kept if psql is in interactive mode. When executing a non-interactive script, processing will immediately stop with an error. This distinction was chosen as a user convenience against typos on the one hand, and a safety mechanism that scripts are not accidentally acting on the wrong database on the other hand.
例子：
=> \c mydb myuser host.dom 6432 => \c service=foo => \c "host=localhost port=5432 dbname=mydb connect_timeout=10 sslmode=disable" => \c postgresql://tom@localhost/mydb?application_name=myapp
Sets the title of any tables being printed as the result of a query or unset any such title. This command is equivalent to \pset title title. (The name of this command derives from "caption", as it was previously only used to set the caption in an HTML table.)
把当前工作目录改为directory。 如果不带参数，则切换到当前用户的主目录。
Tip: 要打印当前的工作目录，可以使用\! pwd。
输出有关当前数据库连接的信息。
Performs a frontend (client) copy. This is an operation that runs an SQL COPY command, but instead of the server reading or writing the specified file, psql reads or writes the file and routes the data between the server and the local file system. This means that file accessibility and privileges are those of the local user, not the server, and no SQL superuser privileges are required.
When program is specified, command is executed by psql and the data passed from or to command is routed between the server and the client. Again, the execution privileges are those of the local user, not the server, and no SQL superuser privileges are required.
For \copy ... from stdin, data rows are read from the same source that issued the command, continuing until \. is read or the stream reaches EOF. This option is useful for populating tables in-line within a SQL script file. For \copy ... to stdout, output is sent to the same place as psql command output, and the COPY count command status is not printed (since it might be confused with a data row). To read/write psql's standard input or output regardless of the current command source or \o option, write from pstdin or to pstdout.
The syntax of this command is similar to that of the SQL COPY command. All options other than the data source/destination are as specified for COPY. Because of this, special parsing rules apply to the \copy command. In particular, psql's variable substitution rules and backslash escapes do not apply.
Tip: This operation is not as efficient as the SQL COPY command because all data must pass through the client/server connection. For large amounts of data the SQL command might be preferable.
显示PostgreSQL的版权 以及发布条款。
For each relation (table, view, index, sequence, or foreign table) or composite type matching the pattern, show all columns, their types, the tablespace (if not the default) and any special attributes such as NOT NULL or defaults. Associated indexes, constraints, rules, and triggers are also shown. For foreign tables, the associated foreign server is shown as well. ("Matching the pattern" is defined in 模式 below.)
For some types of relation, \d shows additional information for each column: column values for sequences, indexed expression for indexes and foreign data wrapper options for foreign tables.
The command form \d+ is identical, except that more information is displayed: any comments associated with the columns of the table are shown, as is the presence of OIDs in the table, the view definition if the relation is a view, a non-default replica identity setting.
By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects.
Note: If \d is used without a pattern argument, it is equivalent to \dtvsE which will show a list of all visible tables, views, sequences and foreign tables. This is purely a convenience measure.
Lists aggregate functions, together with their return type and the data types they operate on. If pattern is specified, only aggregates whose names match the pattern are shown. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects.
Lists tablespaces. If pattern is specified, only tablespaces whose names match the pattern are shown. If + is appended to the command name, each object is listed with its associated permissions.
Lists conversions between character-set encodings. If pattern is specified, only conversions whose names match the pattern are listed. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects. If + is appended to the command name, each object is listed with its associated description.
Lists type casts. If pattern is specified, only casts whose source or target types match the pattern are listed. If + is appended to the command name, each object is listed with its associated description.
Shows the descriptions of objects of type constraint, operator class, operator family, rule, and trigger. All other comments may be viewed by the respective backslash commands for those object types.
\dd displays descriptions for objects matching the pattern, or of visible objects of the appropriate type if no argument is given. But in either case, only objects that have a description are listed. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects.
Descriptions for objects can be created with the COMMENT SQL command.
Lists default access privilege settings. An entry is shown for each role (and schema, if applicable) for which the default privilege settings have been changed from the built-in defaults. If pattern is specified, only entries whose role name or schema name matches the pattern are listed.
The ALTER DEFAULT PRIVILEGES command is used to set default access privileges. The meaning of the privilege display is explained under GRANT.
Lists domains. If pattern is specified, only domains whose names match the pattern are shown. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects. If + is appended to the command name, each object is listed with its associated permissions and description.
In this group of commands, the letters E, i, m, s, t, and v stand for foreign table, index, materialized view, sequence, table, and view, respectively. You can specify any or all of these letters, in any order, to obtain a listing of objects of these types. For example, \dit lists indexes and tables. If + is appended to the command name, each object is listed with its physical size on disk and its associated description, if any. If pattern is specified, only objects whose names match the pattern are listed. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects.
Lists foreign servers (mnemonic: "external servers"). If pattern is specified, only those servers whose name matches the pattern are listed. If the form \des+ is used, a full description of each server is shown, including the server's ACL, type, version, options, and description.
Lists foreign tables (mnemonic: "external tables"). If pattern is specified, only entries whose table name or schema name matches the pattern are listed. If the form \det+ is used, generic options and the foreign table description are also displayed.
Lists user mappings (mnemonic: "external users"). If pattern is specified, only those mappings whose user names match the pattern are listed. If the form \deu+ is used, additional information about each mapping is shown.
| Caution |
\deu+ might also display the user name and password of the remote user, so care should be taken not to disclose them. |
Lists foreign-data wrappers (mnemonic: "external wrappers"). If pattern is specified, only those foreign-data wrappers whose name matches the pattern are listed. If the form \dew+ is used, the ACL, options, and description of the foreign-data wrapper are also shown.
Lists functions, together with their arguments, return types, and function types, which are classified as "agg" (aggregate), "normal", "trigger", or "window". To display only functions of specific type(s), add the corresponding letters a, n, t, or w to the command. If pattern is specified, only functions whose names match the pattern are shown. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects. If the form \df+ is used, additional information about each function is shown, including security classification, volatility, owner, language, source code and description.
Tip: To look up functions taking arguments or returning values of a specific type, use your pager's search capability to scroll through the \df output.
Lists text search configurations. If pattern is specified, only configurations whose names match the pattern are shown. If the form \dF+ is used, a full description of each configuration is shown, including the underlying text search parser and the dictionary list for each parser token type.
Lists text search dictionaries. If pattern is specified, only dictionaries whose names match the pattern are shown. If the form \dFd+ is used, additional information is shown about each selected dictionary, including the underlying text search template and the option values.
Lists text search parsers. If pattern is specified, only parsers whose names match the pattern are shown. If the form \dFp+ is used, a full description of each parser is shown, including the underlying functions and the list of recognized token types.
Lists text search templates. If pattern is specified, only templates whose names match the pattern are shown. If the form \dFt+ is used, additional information is shown about each template, including the underlying function names.
Lists database roles. (Since the concepts of "users" and "groups" have been unified into "roles", this command is now equivalent to \du.) If pattern is specified, only those roles whose names match the pattern are listed. If the form \dg+ is used, additional information is shown about each role; currently this adds the comment for each role.
这是一个\lo_list的别名，这会显示一个 大对象列表。
Lists procedural languages. If pattern is specified, only languages whose names match the pattern are listed. By default, only user-created languages are shown; supply the S modifier to include system objects. If + is appended to the command name, each language is listed with its call handler, validator, access privileges, and whether it is a system object.
Lists schemas (namespaces). If pattern is specified, only schemas whose names match the pattern are listed. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects. If + is appended to the command name, each object is listed with its associated permissions and description, if any.
Lists operators with their operand and result types. If pattern is specified, only operators whose names match the pattern are listed. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects. If + is appended to the command name, additional information about each operator is shown, currently just the name of the underlying function.
Lists collations. If pattern is specified, only collations whose names match the pattern are listed. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects. If + is appended to the command name, each collation is listed with its associated description, if any. Note that only collations usable with the current database's encoding are shown, so the results may vary in different databases of the same installation.
Lists tables, views and sequences with their associated access privileges. If pattern is specified, only tables, views and sequences whose names match the pattern are listed.
The GRANT and REVOKE commands are used to set access privileges. The meaning of the privilege display is explained under GRANT.
Lists defined configuration settings. These settings can be role-specific, database-specific, or both. role-pattern and database-pattern are used to select specific roles and databases to list, respectively. If omitted, or if * is specified, all settings are listed, including those not role-specific or database-specific, respectively.
The ALTER ROLE and ALTER DATABASE commands are used to define per-role and per-database configuration settings.
Lists data types. If pattern is specified, only types whose names match the pattern are listed. If + is appended to the command name, each type is listed with its internal name and size, its allowed values if it is an enum type, and its associated permissions. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects.
Lists database roles. (Since the concepts of "users" and "groups" have been unified into "roles", this command is now equivalent to \dg.) If pattern is specified, only those roles whose names match the pattern are listed. If the form \du+ is used, additional information is shown about each role; currently this adds the comment for each role.
Lists installed extensions. If pattern is specified, only those extensions whose names match the pattern are listed. If the form \dx+ is used, all the objects belonging to each matching extension are listed.
Lists event triggers. If pattern is specified, only those event triggers whose names match the pattern are listed. If + is appended to the command name, each object is listed with its associated description.
If filename is specified, the file is edited; after the editor exits, its content is copied back to the query buffer. If no filename is given, the current query buffer is copied to a temporary file which is then edited in the same fashion.
The new query buffer is then re-parsed according to the normal rules of psql, where the whole buffer is treated as a single line. (Thus you cannot make scripts this way. Use \i for that.) This means that if the query ends with (or contains) a semicolon, it is immediately executed. Otherwise it will merely wait in the query buffer; type semicolon or \g to send it, or \r to cancel.
If a line number is specified, psql will position the cursor on the specified line of the file or query buffer. Note that if a single all-digits argument is given, psql assumes it is a line number, not a file name.
Tip: See under 环境 for how to configure and customize your editor.
Prints the arguments to the standard output, separated by one space and followed by a newline. This can be useful to intersperse information in the output of scripts. For example:
=> \echo `date` Tue Oct 26 21:40:57 CEST 1999
If the first argument is an unquoted -n the trailing newline is not written.
Tip: If you use the \o command to redirect your query output you might wish to use \qecho instead of this command.
This command fetches and edits the definition of the named function, in the form of a CREATE OR REPLACE FUNCTION command. Editing is done in the same way as for \edit. After the editor exits, the updated command waits in the query buffer; type semicolon or \g to send it, or \r to cancel.
The target function can be specified by name alone, or by name and arguments, for example foo(integer, text). The argument types must be given if there is more than one function of the same name.
If no function is specified, a blank CREATE FUNCTION template is presented for editing.
If a line number is specified, psql will position the cursor on the specified line of the function body. (Note that the function body typically does not begin on the first line of the file.)
Tip: See under 环境 for how to configure and customize your editor.
设置客户端字符集编码。如果不带参数，这个命令显示当前编码。
Sets the field separator for unaligned query output. The default is the vertical bar (|). See also \pset for a generic way of setting output options.
Sends the current query input buffer to the server, and optionally stores the query's output in filename or pipes the output to the shell command command. The file or command is written to only if the query successfully returns zero or more tuples, not if the query fails or is a non-data-returning SQL command.
A bare \g is essentially equivalent to a semicolon. A \g with argument is a "one-shot" alternative to the \o command.
Sends the current query input buffer to the server and stores the query's output into psql variables (see 变量). The query to be executed must return exactly one row. Each column of the row is stored into a separate variable, named the same as the column. For example:
=> SELECT 'hello' AS var1, 10 AS var2 -> \gset => \echo :var1 :var2 hello 10
If you specify a prefix, that string is prepended to the query's column names to create the variable names to use:
=> SELECT 'hello' AS var1, 10 AS var2 -> \gset result_ => \echo :result_var1 :result_var2 hello 10
如果一个列结果为 NULL，对应的变量会被重置而不是被设置。
如果查询失败或者不返回行，任何变量都不会被改变。
Gives syntax help on the specified SQL command. If command is not specified, then psql will list all the commands for which syntax help is available. If command is an asterisk (*), then syntax help on all SQL commands is shown.
Note: To simplify typing, commands that consists of several words do not have to be quoted. Thus it is fine to type \help alter table.
Turns on HTML query output format. If the HTML format is already on, it is switched back to the default aligned text format. This command is for compatibility and convenience, but see \pset about setting other output options.
Reads input from the file filename and executes it as though it had been typed on the keyboard.
Note: If you want to see the lines on the screen as they are read you must set the variable ECHO to all.
The \ir command is similar to \i, but resolves relative file names differently. When executing in interactive mode, the two commands behave identically. However, when invoked from a script, \ir interprets file names relative to the directory in which the script is located, rather than the current working directory.
List the databases in the server and show their names, owners, character set encodings, and access privileges. If pattern is specified, only databases whose names match the pattern are listed. If + is appended to the command name, database sizes, default tablespaces, and descriptions are also displayed. (Size information is only available for databases that the current user can connect to.)
Reads the large object with OID loid from the database and
writes it to filename. Note that this is
subtly different from the server function
lo_export, which acts with the permissions
of the user that the database server runs as and on the server's
file system.
Tip: 使用\lo_list可以找出大对象的 OID.
Stores the file into a PostgreSQL large object. Optionally, it associates the given comment with the object. Example:
foo=> \lo_import '/home/peter/pictures/photo.xcf' 'a picture of me' lo_import 152801
The response indicates that the large object received object ID 152801, which can be used to access the newly-created large object in the future. For the sake of readability, it is recommended to always associate a human-readable comment with every object. Both OIDs and comments can be viewed with the \lo_list command.
Note that this command is subtly different from the server-side
lo_import because it acts as the local user
on the local file system, rather than the server's user and file
system.
显示当前存储在数据库中所有 PostgreSQL大对象的列表，还有 提供给它们的任何注释。
从数据库中删除OID loid对应的大对象。
Tip: 使用\lo_list可以找到大对象的 OID。
Arranges to save future query results to the file filename or pipe future results to the shell command command. If no argument is specified, the query output is reset to the standard output.
"Query results" includes all tables, command responses, and notices obtained from the database server, as well as output of various backslash commands that query the database (such as \d), but not error messages.
Tip: 要在查询结果之间散布文本输出，可以使用 \qecho。
向标准输出打印当前的查询缓冲区。
Changes the password of the specified user (by default, the current user). This command prompts for the new password, encrypts it, and sends it to the server as an ALTER ROLE command. This makes sure that the new password does not appear in cleartext in the command history, the server log, or elsewhere.
Prompts the user to supply text, which is assigned to the variable name. An optional prompt string, text, can be specified. (For multiword prompts, surround the text with single quotes.)
By default, \prompt uses the terminal for input and output. However, if the -f command line switch was used, \prompt uses standard input and standard output.
This command sets options affecting the output of query result tables. option indicates which option is to be set. The semantics of value vary depending on the selected option. For some options, omitting value causes the option to be toggled or unset, as described under the particular option. If no such behavior is mentioned, then omitting value just results in the current setting being displayed.
不带任何参数的\pset显示所有打印选项的 当前状态。
可调整的打印选项是：
The value must be a number. In general, the higher the number the more borders and lines the tables will have, but this depends on the particular format. In HTML format, this will translate directly into the border=... attribute; in the other formats only values 0 (no border), 1 (internal dividing lines), and 2 (table frame) make sense. latex and latex-longtable also support a border value of 3 which adds a dividing line between each row.
Sets the target width for the wrapped format, and also the width limit for determining whether output is wide enough to require the pager or switch to the vertical display in expanded auto mode. Zero (the default) causes the target width to be controlled by the environment variable COLUMNS, or the detected screen width if COLUMNS is not set. In addition, if columns is zero then the wrapped format only affects screen output. If columns is nonzero then file and pipe output is wrapped to that width as well.
If value is specified it must be either on or off, which will enable or disable expanded mode, or auto. If value is omitted the command toggles between the on and off settings. When expanded mode is enabled, query results are displayed in two columns, with the column name on the left and the data on the right. This mode is useful if the data wouldn't fit on the screen in the normal "horizontal" mode. In the auto setting, the expanded mode is used whenever the query output is wider than the screen, otherwise the regular mode is used. The auto setting is only effective in the aligned and wrapped formats. In other formats, it always behaves as if the expanded mode is off.
Specifies the field separator to be used in unaligned output format. That way one can create, for example, tab- or comma-separated output, which other programs might prefer. To set a tab as field separator, type \pset fieldsep '\t'. The default field separator is '|' (a vertical bar).
Sets the field separator to use in unaligned output format to a zero byte.
If value is specified it must be either on or off which will enable or disable display of the table footer (the (n rows) count). If value is omitted the command toggles footer display on or off.
Sets the output format to one of unaligned, aligned, wrapped, html, latex (uses tabular), latex-longtable, or troff-ms. Unique abbreviations are allowed. (That would mean one letter is enough.)
unaligned format writes all columns of a row on one line, separated by the currently active field separator. This is useful for creating output that might be intended to be read in by other programs (for example, tab-separated or comma-separated format).
aligned format is the standard, human-readable, nicely formatted text output; this is the default.
wrapped format is like aligned but wraps wide data values across lines to make the output fit in the target column width. The target width is determined as described under the columns option. Note that psql will not attempt to wrap column header titles; therefore, wrapped format behaves the same as aligned if the total width needed for column headers exceeds the target.
The html, latex, latex-longtable, and troff-ms formats put out tables that are intended to be included in documents using the respective mark-up language. They are not complete documents! This might not be necessary in HTML, but in LaTeX you must have a complete document wrapper. latex-longtable also requires the LaTeX longtable and booktabs packages.
Sets the border line drawing style to one of ascii, old-ascii or unicode. Unique abbreviations are allowed. (That would mean one letter is enough.) The default setting is ascii. This option only affects the aligned and wrapped output formats.
ascii style uses plain ASCII characters. Newlines in data are shown using a + symbol in the right-hand margin. When the wrapped format wraps data from one line to the next without a newline character, a dot (.) is shown in the right-hand margin of the first line, and again in the left-hand margin of the following line.
old-ascii style uses plain ASCII characters, using the formatting style used in PostgreSQL 8.4 and earlier. Newlines in data are shown using a : symbol in place of the left-hand column separator. When the data is wrapped from one line to the next without a newline character, a ; symbol is used in place of the left-hand column separator.
unicode style uses Unicode box-drawing characters. Newlines in data are shown using a carriage return symbol in the right-hand margin. When the data is wrapped from one line to the next without a newline character, an ellipsis symbol is shown in the right-hand margin of the first line, and again in the left-hand margin of the following line.
When the border setting is greater than zero, this option also determines the characters with which the border lines are drawn. Plain ASCII characters work everywhere, but Unicode characters look nicer on displays that recognize them.
Sets the string to be printed in place of a null value. The default is to print nothing, which can easily be mistaken for an empty string. For example, one might prefer \pset null '(null)'.
If value is specified it must be either on or off which will enable or disable display of a locale-specific character to separate groups of digits to the left of the decimal marker. If value is omitted the command toggles between regular and locale-specific numeric output.
Controls use of a pager program for query and psql help output. If the environment variable PAGER is set, the output is piped to the specified program. Otherwise a platform-dependent default (such as more) is used.
When the pager option is off, the pager program is not used. When the pager option is on, the pager is used when appropriate, i.e., when the output is to a terminal and will not fit on the screen. The pager option can also be set to always, which causes the pager to be used for all terminal output regardless of whether it fits on the screen. \pset pager without a value toggles pager use on and off.
Specifies the record (line) separator to use in unaligned output format. The default is a newline character.
Sets the record separator to use in unaligned output format to a zero byte.
In HTML format, this specifies attributes
to be placed inside the table tag. This
could for example be cellpadding or
bgcolor. Note that you probably don't want
to specify border here, as that is already
taken care of by \pset border.
If no
value is given,
the table attributes are unset.
In latex-longtable format, this controls the proportional width of each column containing a left-aligned data type. It is specified as a whitespace-separated list of values, e.g. '0.2 0.2 0.6'. Unspecified output columns use the last specified value.
Sets the table title for any subsequently printed tables. This can be used to give your output descriptive tags. If no value is given, the title is unset.
If value is specified it must be either on or off which will enable or disable tuples-only mode. If value is omitted the command toggles between regular and tuples-only output. Regular output includes extra information such as column headers, titles, and various footers. In tuples-only mode, only actual table data is shown.
Illustrations of how these different formats look can be seen in the 例子 section.
Tip: There are various shortcut commands for \pset. See \a, \C, \H, \t, \T, and \x.
Quits the psql program. In a script file, only execution of that script is terminated.
This command is identical to \echo except that the output will be written to the query output channel, as set by \o.
Resets (clears) the query buffer.
Print psql's command line history to filename. If filename is omitted, the history is written to the standard output (using the pager if appropriate). This command is not available if psql was built without Readline support.
Sets the psql variable name to value, or if more than one value is given, to the concatenation of all of them. If only one argument is given, the variable is set with an empty value. To unset a variable, use the \unset command.
\set without any arguments displays the names and values of all currently-set psql variables.
Valid variable names can contain letters, digits, and underscores. See the section 变量 below for details. Variable names are case-sensitive.
Although you are welcome to set any variable to anything you want, psql treats several variables as special. They are documented in the section about variables.
Note: This command is unrelated to the SQL command SET.
Sets the environment variable name to value, or if the value is not supplied, unsets the environment variable. Example:
testdb=> \setenv PAGER less testdb=> \setenv LESS -imx4F
This command fetches and shows the definition of the named function, in the form of a CREATE OR REPLACE FUNCTION command. The definition is printed to the current query output channel, as set by \o.
The target function can be specified by name alone, or by name and arguments, for example foo(integer, text). The argument types must be given if there is more than one function of the same name.
If + is appended to the command name, then the output lines are numbered, with the first line of the function body being line 1.
Toggles the display of output column name headings and row count footer. This command is equivalent to \pset tuples_only and is provided for convenience.
Specifies attributes to be placed within the
table tag in HTML
output format. This command is equivalent to \pset
tableattr table_options.
Without parameter, toggles a display of how long each SQL statement takes, in milliseconds. With parameter, sets same.
Unsets (deletes) the psql variable name.
Outputs the current query buffer to the file filename or pipes it to the shell command command.
Repeatedly execute the current query buffer (like \g) until interrupted or the query fails. Wait the specified number of seconds (default 2) between executions.
Sets or toggles expanded table formatting mode. As such it is equivalent to \pset expanded.
Lists tables, views and sequences with their associated access privileges. If a pattern is specified, only tables, views and sequences whose names match the pattern are listed.
This is an alias for \dp ("display privileges").
Escapes to a separate shell or executes the shell command command. The arguments are not further interpreted; the shell will see them as-is. In particular, the variable substitution rules and backslash escapes do not apply.
Shows help information about the backslash commands.
The various \d commands accept a pattern parameter to specify the object name(s) to be displayed. In the simplest case, a pattern is just the exact name of the object. The characters within a pattern are normally folded to lower case, just as in SQL names; for example, \dt FOO will display the table named foo. As in SQL names, placing double quotes around a pattern stops folding to lower case. Should you need to include an actual double quote character in a pattern, write it as a pair of double quotes within a double-quote sequence; again this is in accord with the rules for SQL quoted identifiers. For example, \dt "FOO""BAR" will display the table named FOO"BAR (not foo"bar). Unlike the normal rules for SQL names, you can put double quotes around just part of a pattern, for instance \dt FOO"FOO"BAR will display the table named fooFOObar.
Whenever the pattern parameter is omitted completely, the \d commands display all objects that are visible in the current schema search path — this is equivalent to using * as the pattern. (An object is said to be visible if its containing schema is in the search path and no object of the same kind and name appears earlier in the search path. This is equivalent to the statement that the object can be referenced by name without explicit schema qualification.) To see all objects in the database regardless of visibility, use *.* as the pattern.
Within a pattern, * matches any sequence of characters (including no characters) and ? matches any single character. (This notation is comparable to Unix shell file name patterns.) For example, \dt int* displays tables whose names begin with int. But within double quotes, * and ? lose these special meanings and are just matched literally.
A pattern that contains a dot (.) is interpreted as a schema name pattern followed by an object name pattern. For example, \dt foo*.*bar* displays all tables whose table name includes bar that are in schemas whose schema name starts with foo. When no dot appears, then the pattern matches only objects that are visible in the current schema search path. Again, a dot within double quotes loses its special meaning and is matched literally.
Advanced users can use regular-expression notations such as character classes, for example [0-9] to match any digit. All regular expression special characters work as specified in Section 9.7.3, except for . which is taken as a separator as mentioned above, * which is translated to the regular-expression notation .*, ? which is translated to ., and $ which is matched literally. You can emulate these pattern characters at need by writing ? for ., (R+|) for R*, or (R|) for R?. $ is not needed as a regular-expression character since the pattern must match the whole name, unlike the usual interpretation of regular expressions (in other words, $ is automatically appended to your pattern). Write * at the beginning and/or end if you don't wish the pattern to be anchored. Note that within double quotes, all regular expression special characters lose their special meanings and are matched literally. Also, the regular expression special characters are matched literally in operator name patterns (i.e., the argument of \do).
psql provides variable substitution features similar to common Unix command shells. Variables are simply name/value pairs, where the value can be any string of any length. The name must consist of letters (including non-Latin letters), digits, and underscores.
To set a variable, use the psql meta-command \set. For example,
testdb=> \set foo bar
sets the variable foo to the value bar. To retrieve the content of the variable, precede the name with a colon, for example:
testdb=> \echo :foo bar
This works in both regular SQL commands and meta-commands; there is more detail in SQL Interpolation, below.
If you call \set without a second argument, the variable is set, with an empty string as value. To unset (i.e., delete) a variable, use the command \unset. To show the values of all variables, call \set without any argument.
Note: The arguments of \set are subject to the same substitution rules as with other commands. Thus you can construct interesting references such as \set :foo 'something' and get "soft links" or "variable variables" of Perl or PHP fame, respectively. Unfortunately (or fortunately?), there is no way to do anything useful with these constructs. On the other hand, \set bar :foo is a perfectly valid way to copy a variable.
A number of these variables are treated specially by psql. They represent certain option settings that can be changed at run time by altering the value of the variable, or in some cases represent changeable state of psql. Although you can use these variables for other purposes, this is not recommended, as the program behavior might grow really strange really quickly. By convention, all specially treated variables' names consist of all upper-case ASCII letters (and possibly digits and underscores). To ensure maximum compatibility in the future, avoid using such variable names for your own purposes. A list of all specially treated variables follows.
When on (the default), each SQL command is automatically committed upon successful completion. To postpone commit in this mode, you must enter a BEGIN or START TRANSACTION SQL command. When off or unset, SQL commands are not committed until you explicitly issue COMMIT or END. The autocommit-off mode works by issuing an implicit BEGIN for you, just before any command that is not already in a transaction block and is not itself a BEGIN or other transaction-control command, nor a command that cannot be executed inside a transaction block (such as VACUUM).
Note: In autocommit-off mode, you must explicitly abandon any failed transaction by entering ABORT or ROLLBACK. Also keep in mind that if you exit the session without committing, your work will be lost.
Note: The autocommit-on mode is PostgreSQL's traditional behavior, but autocommit-off is closer to the SQL spec. If you prefer autocommit-off, you might wish to set it in the system-wide psqlrc file or your ~/.psqlrc file.
Determines which letter case to use when completing an SQL key word. If set to lower or upper, the completed word will be in lower or upper case, respectively. If set to preserve-lower or preserve-upper (the default), the completed word will be in the case of the word already entered, but words being completed without anything entered will be in lower or upper case, respectively.
The name of the database you are currently connected to. This is set every time you connect to a database (including program start-up), but can be unset.
If set to all, all nonempty input lines are printed to standard output as they are read. (This does not apply to lines read interactively.) To select this behavior on program start-up, use the switch -a. If set to queries, psql prints each query to standard output as it is sent to the server. The switch for this is -e.
When this variable is set to on and a backslash command queries the database, the query is first shown. This feature helps you to study PostgreSQL internals and provide similar functionality in your own programs. (To select this behavior on program start-up, use the switch -E.) If you set the variable to the value noexec, the queries are just shown but are not actually sent to the server and executed.
The current client character set encoding.
If this variable is set to an integer value > 0, the results of SELECT queries are fetched and displayed in groups of that many rows, rather than the default behavior of collecting the entire result set before display. Therefore only a limited amount of memory is used, regardless of the size of the result set. Settings of 100 to 1000 are commonly used when enabling this feature. Keep in mind that when using this feature, a query might fail after having already displayed some rows.
Tip: Although you can use any output format with this feature, the default aligned format tends to look bad because each group of FETCH_COUNT rows will be formatted separately, leading to varying column widths across the row groups. The other output formats work better.
If this variable is set to ignorespace, lines which begin with a space are not entered into the history list. If set to a value of ignoredups, lines matching the previous history line are not entered. A value of ignoreboth combines the two options. If unset, or if set to any other value than those above, all lines read in interactive mode are saved on the history list.
Note: This feature was shamelessly plagiarized from Bash.
The file name that will be used to store the history list. The default value is ~/.psql_history. For example, putting:
\set HISTFILE ~/.psql_history- :DBNAME
in ~/.psqlrc will cause psql to maintain a separate history for each database.
Note: This feature was shamelessly plagiarized from Bash.
The number of commands to store in the command history. The default value is 500.
Note: This feature was shamelessly plagiarized from Bash.
The database server host you are currently connected to. This is set every time you connect to a database (including program start-up), but can be unset.
If unset, sending an EOF character (usually Control+D) to an interactive session of psql will terminate the application. If set to a numeric value, that many EOF characters are ignored before the application terminates. If the variable is set but has no numeric value, the default is 10.
Note: This feature was shamelessly plagiarized from Bash.
The value of the last affected OID, as returned from an INSERT or \lo_import command. This variable is only guaranteed to be valid until after the result of the next SQL command has been displayed.
When set to on, if a statement in a transaction block generates an error, the error is ignored and the transaction continues. When set to interactive, such errors are only ignored in interactive sessions, and not when reading script files. When unset or set to off, a statement in a transaction block that generates an error aborts the entire transaction. The error rollback mode works by issuing an implicit SAVEPOINT for you, just before each command that is in a transaction block, and then rolling back to the savepoint if the command fails.
By default, command processing continues after an error. When this variable is set to on, processing will instead stop immediately. In interactive mode, psql will return to the command prompt; otherwise, psql will exit, returning error code 3 to distinguish this case from fatal error conditions, which are reported using error code 1. In either case, any currently running scripts (the top-level script, if any, and any other scripts which it may have in invoked) will be terminated immediately. If the top-level command string contained multiple SQL commands, processing will stop with the current command.
The database server port to which you are currently connected. This is set every time you connect to a database (including program start-up), but can be unset.
These specify what the prompts psql issues should look like. See 提示符 below.
Setting this variable to on is equivalent to the command line option -q. It is probably not too useful in interactive mode.
Setting this variable to on is equivalent to the command line option -S.
Setting this variable to on is equivalent to the command line option -s.
The database user you are currently connected as. This is set every time you connect to a database (including program start-up), but can be unset.
This variable can be set to the values default, verbose, or terse to control the verbosity of error reports.
A key feature of psql variables is that you can substitute ("interpolate") them into regular SQL statements, as well as the arguments of meta-commands. Furthermore, psql provides facilities for ensuring that variable values used as SQL literals and identifiers are properly quoted. The syntax for interpolating a value without any quoting is to prepend the variable name with a colon (:). For example,
testdb=> \set foo 'my_table' testdb=> SELECT * FROM :foo;
would query the table my_table. Note that this may be unsafe: the value of the variable is copied literally, so it can contain unbalanced quotes, or even backslash commands. You must make sure that it makes sense where you put it.
When a value is to be used as an SQL literal or identifier, it is safest to arrange for it to be quoted. To quote the value of a variable as an SQL literal, write a colon followed by the variable name in single quotes. To quote the value as an SQL identifier, write a colon followed by the variable name in double quotes. These constructs deal correctly with quotes and other special characters embedded within the variable value. The previous example would be more safely written this way:
testdb=> \set foo 'my_table' testdb=> SELECT * FROM :"foo";
Variable interpolation will not be performed within quoted SQL literals and identifiers. Therefore, a construction such as ':foo' doesn't work to produce a quoted literal from a variable's value (and it would be unsafe if it did work, since it wouldn't correctly handle quotes embedded in the value).
One example use of this mechanism is to copy the contents of a file into a table column. First load the file into a variable and then interpolate the variable's value as a quoted string:
testdb=> \set content `cat my_file.txt` testdb=> INSERT INTO my_table VALUES (:'content');
(Note that this still won't work if my_file.txt contains NUL bytes. psql does not support embedded NUL bytes in variable values.)
Since colons can legally appear in SQL commands, an apparent attempt at interpolation (that is, :name, :'name', or :"name") is not replaced unless the named variable is currently set. In any case, you can escape a colon with a backslash to protect it from substitution.
The colon syntax for variables is standard SQL for embedded query languages, such as ECPG. The colon syntaxes for array slices and type casts are PostgreSQL extensions, which can sometimes conflict with the standard usage. The colon-quote syntax for escaping a variable's value as an SQL literal or identifier is a psql extension.
The prompts psql issues can be customized to your preference. The three variables PROMPT1, PROMPT2, and PROMPT3 contain strings and special escape sequences that describe the appearance of the prompt. Prompt 1 is the normal prompt that is issued when psql requests a new command. Prompt 2 is issued when more input is expected during command input because the command was not terminated with a semicolon or a quote was not closed. Prompt 3 is issued when you run an SQL COPY command and you are expected to type in the row values on the terminal.
The value of the selected prompt variable is printed literally, except where a percent sign (%) is encountered. Depending on the next character, certain other text is substituted instead. Defined substitutions are:
The full host name (with domain name) of the database server, or [local] if the connection is over a Unix domain socket, or [local:/dir/name], if the Unix domain socket is not at the compiled in default location.
The host name of the database server, truncated at the first dot, or [local] if the connection is over a Unix domain socket.
The port number at which the database server is listening.
The database session user name. (The expansion of this value might change during a database session as the result of the command SET SESSION AUTHORIZATION.)
The name of the current database.
Like %/, but the output is ~ (tilde) if the database is your default database.
If the session user is a database superuser, then a #, otherwise a >. (The expansion of this value might change during a database session as the result of the command SET SESSION AUTHORIZATION.)
In prompt 1 normally =, but ^ if in single-line mode, and ! if the session is disconnected from the database (which can happen if \connect fails). In prompt 2 the sequence is replaced by -, *, a single quote, a double quote, or a dollar sign, depending on whether psql expects more input because the command wasn't terminated yet, because you are inside a /* ... */ comment, or because you are inside a quoted or dollar-escaped string. In prompt 3 the sequence doesn't produce anything.
Transaction status: an empty string when not in a transaction block, or * when in a transaction block, or ! when in a failed transaction block, or ? when the transaction state is indeterminate (for example, because there is no connection).
The character with the indicated octal code is substituted.
The value of the psql variable name. See the section 变量 for details.
The output of command, similar to ordinary "back-tick" substitution.
Prompts can contain terminal control characters which, for example, change the color, background, or style of the prompt text, or change the title of the terminal window. In order for the line editing features of Readline to work properly, these non-printing control characters must be designated as invisible by surrounding them with %[ and %]. Multiple pairs of these can occur within the prompt. For example:
testdb=> \set PROMPT1 '%[%033[1;33;40m%]%n@%/%R%[%033[0m%]%# '
results in a boldfaced (1;) yellow-on-black (33;40) prompt on VT100-compatible, color-capable terminals.
To insert a percent sign into your prompt, write %%. The default prompts are '%/%R%# ' for prompts 1 and 2, and '>> ' for prompt 3.
Note: This feature was shamelessly plagiarized from tcsh.
psql supports the Readline library for convenient line editing and retrieval. The command history is automatically saved when psql exits and is reloaded when psql starts up. Tab-completion is also supported, although the completion logic makes no claim to be an SQL parser. The queries generated by tab-completion can also interfere with other SQL commands, e.g. SET TRANSACTION ISOLATION LEVEL. If for some reason you do not like the tab completion, you can turn it off by putting this in a file named .inputrc in your home directory:
$if psql set disable-completion on $endif
(This is not a psql but a Readline feature. Read its documentation for further details.)
If \pset columns is zero, controls the width for the wrapped format and width for determining if wide output requires the pager or should be switched to the vertical format in expanded auto mode.
If the query results do not fit on the screen, they are piped through this command. Typical values are more or less. The default is platform-dependent. The use of the pager can be disabled by using the \pset command.
Default connection parameters (see Section 31.14).
Editor used by the \e and \ef commands. The variables are examined in the order listed; the first that is set is used.
The built-in default editors are vi on Unix systems and notepad.exe on Windows systems.
When \e or \ef is used with a line number argument, this variable specifies the command-line argument used to pass the starting line number to the user's editor. For editors such as Emacs or vi, this is a plus sign. Include a trailing space in the value of the variable if there needs to be space between the option name and the line number. Examples:
PSQL_EDITOR_LINENUMBER_ARG='+' PSQL_EDITOR_LINENUMBER_ARG='--line '
The default is + on Unix systems (corresponding to the default editor vi, and useful for many other common editors); but there is no default on Windows systems.
Alternative location for the command history file. Tilde (~) expansion is performed.
Alternative location of the user's .psqlrc file. Tilde (~) expansion is performed.
Command executed by the \! command.
Directory for storing temporary files. The default is /tmp.
This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Section 31.14).
Unless it is passed an -X or -c option, psql attempts to read and execute commands from the system-wide startup file (psqlrc) and then the user's personal startup file (~/.psqlrc), after connecting to the database but before accepting normal commands. These files can be used to set up the client and/or the server to taste, typically with \set and SET commands.
The system-wide startup file is named psqlrc and is sought in the installation's "system configuration" directory, which is most reliably identified by running pg_config --sysconfdir. By default this directory will be ../etc/ relative to the directory containing the PostgreSQL executables. The name of this directory can be set explicitly via the PGSYSCONFDIR environment variable.
The user's personal startup file is named .psqlrc and is sought in the invoking user's home directory. On Windows, which lacks such a concept, the personal startup file is named %APPDATA%\postgresql\psqlrc.conf. The location of the user's startup file can be set explicitly via the PSQLRC environment variable.
Both the system-wide startup file and the user's personal startup file can be made psql-version-specific by appending a dash and the PostgreSQL major or minor release number to the file name, for example ~/.psqlrc-9.2 or ~/.psqlrc-9.2.5. The most specific version-matching file will be read in preference to a non-version-specific file.
The command-line history is stored in the file ~/.psql_history, or %APPDATA%\postgresql\psql_history on Windows.
The location of the history file can be set explicitly via the PSQL_HISTORY environment variable.
In an earlier life psql allowed the first argument of a single-letter backslash command to start directly after the command, without intervening whitespace. As of PostgreSQL 8.4 this is no longer allowed.
psql works best with servers of the same or an older major version. Backslash commands are particularly likely to fail if the server is of a newer version than psql itself. However, backslash commands of the \d family should work with servers of versions back to 7.4, though not necessarily with servers newer than psql itself. The general functionality of running SQL commands and displaying query results should also work with servers of a newer major version, but this cannot be guaranteed in all cases.
If you want to use psql to connect to several servers of different major versions, it is recommended that you use the newest version of psql. Alternatively, you can keep a copy of psql from each major version around and be sure to use the version that matches the respective server. But in practice, this additional complication should not be necessary.
psql is built as a "console application". Since the Windows console windows use a different encoding than the rest of the system, you must take special care when using 8-bit characters within psql. If psql detects a problematic console code page, it will warn you at startup. To change the console code page, two things are necessary:
Set the code page by entering cmd.exe /c chcp 1252. (1252 is a code page that is appropriate for German; replace it with your value.) If you are using Cygwin, you can put this command in /etc/profile.
Set the console font to Lucida Console, because the raster font does not work with the ANSI code page.
第一个例子展示如何把一个命令分布在多个输入行上。注意提示符的变化：
testdb=> CREATE TABLE my_table ( testdb(> first integer not null default 0, testdb(> second text) testdb-> ; CREATE TABLE
现在再看看表定义：
testdb=> \d my_table
Table "my_table"
Attribute | Type | Modifier
-----------+---------+--------------------
first | integer | not null default 0
second | text |
现在我们把提示符改成更有趣的东西：
testdb=> \set PROMPT1 '%n@%m %~%R%# ' peter@localhost testdb=>
假设已经用数据填充了表并且想要看看数据：
peter@localhost testdb=> SELECT * FROM my_table;
first | second
-------+--------
1 | one
2 | two
3 | three
4 | four
(4 rows)
可以通过使用\pset命令以不同的 方式显示表：
peter@localhost testdb=> \pset border 2
Border style is 2.
peter@localhost testdb=> SELECT * FROM my_table;
+-------+--------+
| first | second |
+-------+--------+
| 1 | one |
| 2 | two |
| 3 | three |
| 4 | four |
+-------+--------+
(4 rows)
peter@localhost testdb=> \pset border 0
Border style is 0.
peter@localhost testdb=> SELECT * FROM my_table;
first second
----- ------
1 one
2 two
3 three
4 four
(4 rows)
peter@localhost testdb=> \pset border 1
Border style is 1.
peter@localhost testdb=> \pset format unaligned
Output format is unaligned.
peter@localhost testdb=> \pset fieldsep ","
Field separator is ",".
peter@localhost testdb=> \pset tuples_only
Showing only tuples.
peter@localhost testdb=> SELECT second, first FROM my_table;
one,1
two,2
three,3
four,4或者，使用短命令：
peter@localhost testdb=> \a \t \x Output format is aligned. Tuples only is off. Expanded display is on. peter@localhost testdb=> SELECT * FROM my_table; -[ RECORD 1 ]- first | 1 second | one -[ RECORD 2 ]- first | 2 second | two -[ RECORD 3 ]- first | 3 second | three -[ RECORD 4 ]- first | 4 second | four