>查看psql命令行界面支持哪些命令？
\??? 具体支持的命令可以参考末尾附加部分
\h xxxcommand? 查看命令使用语法
>统计SQL语句运行耗时
\timing on --打开耗时统计? 执行完成后，后面在psql命令行上执行的SQL语句就会有时间统计了。
\timing off? --关闭耗时统计
?>执行shell命令
\!? 加上具体的命令
***切换目录在\!中不生效，可以直接使用\cd 加上目录名
>显示表定义等
\dt+? 模式名.表名规则
\d 加上具体表名
\d+? 加上具体表名
>重复执行SQL语句-watch
postgres=# select count(*) from pg_settings;
?count
-------
?? 271
(1 row)
postgres=# \watch 10
Fri Oct? 8 23:08:02 2021 (every 10s)
?count
-------
?? 271
(1 row)
Fri Oct? 8 23:08:12 2021 (every 10s)
?count
-------
?? 271
(1 row)
?
>事务自动提交控制
postgresql 默认情况下，是自动提交的。
\set AUTOCOMMIT off
ROLLBACK;
COMMIT;
\set AUTOCOMMIT on
>附加? 支持的命令 其中标红的重点关注一下用法。
postgres-# \?
General
? \copyright???????????? show PostgreSQL usage and distribution terms
? \crosstabview [COLUMNS] execute query and display results in crosstab
? \errverbose??????????? show most recent error message at maximum verbosity
? \g [FILE] or ;???????? execute query (and send results to file or |pipe)
? \gexec???????????????? execute query, then execute each value in its result
? \gset [PREFIX]???????? execute query and store results in psql variables
? \gx [FILE]???????????? as \g, but forces expanded output mode
? \q???????????????????? quit psql
? \watch [SEC]?????????? execute query every SEC seconds
Help
? \? [commands]????????? show help on backslash commands
? \? options???????????? show help on psql command-line options
? \? variables?????????? show help on special variables
? \h [NAME]????????????? help on syntax of SQL commands, * for all commands
?
Query Buffer
? \e [FILE] [LINE]?????? edit the query buffer (or file) with external editor
? \ef [FUNCNAME [LINE]]? edit function definition with external editor
? \ev [VIEWNAME [LINE]]? edit view definition with external editor
? \p???????????????????? show the contents of the query buffer
? \r???????????????????? reset (clear) the query buffer
? \s [FILE]????????????? display history or save it to file
? \w FILE??????????????? write query buffer to file
Input/Output
? \copy ...????????????? perform SQL COPY with data stream to the client host
? \echo [STRING]???????? write string to standard output
? \i FILE??????????????? execute commands from file
? \ir FILE?????????????? as \i, but relative to location of current script
? \o [FILE]????????????? send all query results to file or |pipe
? \qecho [STRING]??????? write string to query output stream (see \o)
Conditional
? \if EXPR?????????????? begin conditional block
? \elif EXPR???????????? alternative within current conditional block
? \else????????????????? final alternative within current conditional block
? \endif???????????????? end conditional block
Informational
? (options: S = show system objects, + = additional detail)
? \d[S+]???????????????? list tables, views, and sequences
? \d[S+]? NAME?????????? describe table, view, sequence, or index
? \da[S]? [PATTERN]????? list aggregates
? \dA[+]? [PATTERN]????? list access methods
? \db[+]? [PATTERN]????? list tablespaces
? \dc[S+] [PATTERN]????? list conversions
? \dC[+]? [PATTERN]????? list casts
? \dd[S]? [PATTERN]????? show object descriptions not displayed elsewhere
? \dD[S+] [PATTERN]????? list domains
? \ddp??? [PATTERN]????? list default privileges
? \dE[S+] [PATTERN]????? list foreign tables
? \det[+] [PATTERN]????? list foreign tables
? \des[+] [PATTERN]????? list foreign servers
? \deu[+] [PATTERN]????? list user mappings
? \dew[+] [PATTERN]????? list foreign-data wrappers
? \df[antw][S+] [PATRN]? list [only agg/normal/trigger/window] functions
? \dF[+]? [PATTERN]????? list text search configurations
? \dFd[+] [PATTERN]????? list text search dictionaries
? \dFp[+] [PATTERN]????? list text search parsers
? \dFt[+] [PATTERN]????? list text search templates
? \dg[S+] [PATTERN]????? list roles
? \di[S+] [PATTERN]????? list indexes
? \dl??????????????????? list large objects, same as \lo_list
? \dL[S+] [PATTERN]????? list procedural languages
? \dm[S+] [PATTERN]????? list materialized views
? \dn[S+] [PATTERN]????? list schemas
? \do[S]? [PATTERN]????? list operators
? \dO[S+] [PATTERN]????? list collations
? \dp???? [PATTERN]????? list table, view, and sequence access privileges
? \drds [PATRN1 [PATRN2]] list per-database role settings
? \dRp[+] [PATTERN]????? list replication publications
? \dRs[+] [PATTERN]????? list replication subscriptions
? \ds[S+] [PATTERN]????? list sequences
? \dt[S+] [PATTERN]????? list tables
? \dT[S+] [PATTERN]????? list data types
? \du[S+] [PATTERN]????? list roles
? \dv[S+] [PATTERN]????? list views
? \dx[+]? [PATTERN]????? list extensions
? \dy???? [PATTERN]????? list event triggers
? \l[+]?? [PATTERN]????? list databases
? \sf[+]? FUNCNAME?????? show a function's definition
? \sv[+]? VIEWNAME?????? show a view's definition
? \z????? [PATTERN]????? same as \dp
Formatting
? \a???????????????????? toggle between unaligned and aligned output mode
? \C [STRING]??????????? set table title, or unset if none
? \f [STRING]??????????? show or set field separator for unaligned query output
? \H???????????????????? toggle HTML output mode (currently off)
? \pset [NAME [VALUE]]?? set table output option
???????????????????????? (NAME := {border|columns|expanded|fieldsep|fieldsep_zero|
???????????????????????? footer|format|linestyle|null|numericlocale|pager|
???????????????????????? pager_min_lines|recordsep|recordsep_zero|tableattr|title|
???????????????????????? tuples_only|unicode_border_linestyle|
???????????????????????? unicode_column_linestyle|unicode_header_linestyle})
? \t [on|off]??????????? show only rows (currently off)
? \T [STRING]??????????? set HTML <table> tag attributes, or unset if none
? \x [on|off|auto]?????? toggle expanded output (currently off)
Connection
? \c[onnect] {[DBNAME|- USER|- HOST|- PORT|-] | conninfo}
???????????????????????? connect to new database (currently "postgres")
? \conninfo????????????? display information about current connection
? \encoding [ENCODING]?? show or set client encoding
? \password [USERNAME]?? securely change the password for a user
Operating System
? \cd [DIR]????????????? change the current working directory
? \setenv NAME [VALUE]?? set or unset environment variable
? \timing [on|off]?????? toggle timing of commands (currently off)
? \! [COMMAND]?????????? execute command in shell or start interactive shell
Variables
? \prompt [TEXT] NAME??? prompt user to set internal variable
? \set [NAME [VALUE]]??? set internal variable, or list all if no parameters
? \unset NAME??????????? unset (delete) internal variable
Large Objects
? \lo_export LOBOID FILE
? \lo_import FILE [COMMENT]
? \lo_list
? \lo_unlink LOBOID????? large object operations