Postgresql commands - psql commands
Psql is a terminal that may be used to interface with the PostgreSQL database. It is used to more quickly and efficiently query data from the PostgreSQL database server. We'll examine some of the most used Psql commands.
Below is a table containing the most used Psql commands:
Command | Description | Additional Information |
psql -d database -U user -W | Connects to a database under a specific user | -d: used to state the database name -U:used to state the database user
|
psql -h host -d database -U user -W | Connect to a database on a different host. | -h: used to specify the host -d: used to specify the name of the database -U: Used to identify the database user
|
psql -U user -h host “dbname=db sslmode=require” | use SSL mode for the connection | -h: used to state the host -U:used to state the database user
|
\c dbname | Switch connection to a new database
|
|
\l | List available databases |
|
\dt | List available tables |
|
\d | table_name Describe a table such as a column, type, modifiers of columns, etc.
|
|
\dn | List every scheme in the connected database. |
|
\df
| The current database's available functions are listed. |
|
\dv | List the database's current views that are available.
|
|
\du | List all users and their assign roles |
|
SELECT version(); | Retrieve the current version of PostgreSQL server |
|
\g | Execute the last command again |
|
\s | Display command history |
|
\s filename
| Save the command history to a file |
|
\i filename
| Execute psql commands from a file |
|
\? | Know all available psql commands
|
|
\h | Get help | Eg:to get detailed information on ALTER TABLE statement use the \h ALTER TABLE |
\e | Edit command in your own editor |
|
\a | Switch from aligned to non-aligned column output |
|
\H | Switch the output to HTML format |
|
\q | Exit psql shell
|
|
Examples:
- \c
Output:
You are now connected to database "db_3yn8kpgq9_3ynf8sbza" as user "user_3yn8kpgq9_3ynf8sbza". |
2. \df
Output:
List of functions
Schema | Name | Result data type | Argument data types | Type
--------+------+------------------+---------------------+------
(0 rows)
|
3. SELECT Version()
Output:
version
-----------------------------------------------------------------------------------------------------------------------------
PostgreSQL 14.5 (Debian 14.5-2.pgdg110+2) on x86_64-pc-linux-gnu, compiled by gcc (Debian 10.2.1-6) 10.2.1 20210110, 64-bit
(1 row) |
4. \?
Output:
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)
\gdesc describe result of query, without executing it
\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[anptw][S+] [PATRN] list [only agg/normal/procedures/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
\dP[itn+] [PATTERN] list [only index/table] partitioned relations [n=nested]
\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
(border|columns|csv_fieldsep|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 "db_3yn8kpgry_3ynf8ypap")
\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
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Conclusion:
Postgresql commands with description and additional information is discussed.
