PostgreSQL commands
Access the PostgreSQL server from psql with a specific user:
psql -U [username];
For example, the following command uses the postgres user to access the PostgreSQL database server:
psql -U postgres
dwd
Connect to a specific database:
\c database_name;For example, the following command connects to the dvdrental database:
\c dvdrental;You are now connected to database "dvdrental" as user "postgres".
To quit the psql:
\q
List all databases in the PostgreSQL database server
\l
List all schemas:
\dn
List all stored procedures and functions:
\df
List all views:
\dv
Lists all tables in a current database.
\dt
Or to get more information on tables in the current database:
\dt+
Get detailed information on a table.
\d+ table_name
Show a stored procedure or function code:
\df+ function_name
Show query output in the pretty-format:
\x
List all users:
\du
Create a new role:
CREATE ROLE role_name;
Create a new role with a username and password:
CREATE ROLE username NOINHERIT LOGIN PASSWORD password;
Change role for the current session to the new_role:
SET ROLE new_role;
Allow role_1 to set its role as role_2:
GRANT role_2 TO role_1;
Managing databases
Create a new database:
CREATE DATABASE [IF NOT EXISTS] db_name;
Delete a database permanently:
DROP DATABASE [IF EXISTS] db_name;
Managing tables
Create a new table or a temporary table
CREATE [TEMP] TABLE [IF NOT EXISTS] table_name(
pk SERIAL PRIMARY KEY,
c1 type(size) NOT NULL,
c2 type(size) NULL,
...
);
Add a new column to a table:
ALTER TABLE table_name ADD COLUMN new_column_name TYPE;
Drop a column in a table:
ALTER TABLE table_name DROP COLUMN column_name;
Rename a column:
ALTER TABLE table_name RENAME column_name TO new_column_name;
Set or remove a default value for a column:
ALTER TABLE table_name ALTER COLUMN [SET DEFAULT value | DROP DEFAULT]
Add a primary key to a table.
ALTER TABLE table_name ADD PRIMARY KEY (column,...);
Remove the primary key from a table.
ALTER TABLE table_name
DROP CONSTRAINT primary_key_constraint_name;
Rename a table.
ALTER TABLE table_name RENAME TO new_table_name;
Drop a table and its dependent objects:
DROPTABLE [IF EXISTS] table_name CASCADE;
Managing views
Create a view:
CREATE OR REPLACE view_name AS
query;
Create a recursive view:
CREATE RECURSIVE VIEW view_name(column_list) AS
SELECT column_list;
Create a materialized view:
CREATE MATERIALIZED VIEW view_name
AS
query
WITH [NO] DATA;
Refresh a materialized view:
REFRESH MATERIALIZED VIEW CONCURRENTLY view_name;
Drop a view:
DROP VIEW [ IF EXISTS ] view_name;
Drop a materialized view:
DROP MATERIALIZED VIEW view_name;
Rename a view:
ALTER VIEW view_name RENAME TO new_name;
Managing indexes
Creating an index with the specified name on a table
CREATE [UNIQUE] INDEX index_name
ON table (column,...)
Removing a specified index from a table
DROP INDEX index_name;
Querying data from tables
Query all data from a table:
SELECT * FROM table_name;
Query data from specified columns of all rows in a table:
SELECT column_list
FROM table;
Query data and select only unique rows:
SELECT DISTINCT (column)
FROM table;
Query data from a table with a filter:
SELECT *
FROM table
WHERE condition;
Assign an alias to a column in the result set:
SELECT column_1 AS new_column_1, ...
FROM table;
Query data using the LIKE operator:
SELECT * FROM table_name
WHERE column LIKE '%value%'
Query data using the BETWEEN operator:
SELECT * FROM table_name
WHERE column BETWEEN low AND high;
Query data using the IN operator:
SELECT * FROM table_name
WHERE column IN (value1, value2,...);
Constrain the returned rows with the LIMIT clause:
SELECT * FROM table_name
LIMIT limit OFFSET offset
ORDER BY column_name;
Query data from multiple using the inner join, left join, full outer join, cross join and natural join:
SELECT *
FROM table1
INNER JOIN table2 ON conditions
SELECT *
FROM table1
LEFT JOIN table2 ON conditions
SELECT *
FROM table1
FULL OUTER JOIN table2 ON conditions
SELECT *
FROM table1
CROSS JOIN table2;
SELECT *
FROM table1
NATURAL JOIN table2;
Return the number of rows of a table.
SELECT COUNT (*)
FROM table_name;
Sort rows in ascending or descending order:
SELECT select_list
FROM table
ORDER BY column ASC [DESC], column2 ASC [DESC],...;
Group rows using GROUP BY clause.
SELECT *
FROM table
GROUP BY column_1, column_2, ...;
Filter groups using the HAVING clause.
SELECT *
FROM table
GROUP BY column_1
HAVING condition;
Set operations
Combine the result set of two or more queries with UNION operator:
SELECT * FROM table1
UNION
SELECT * FROM table2;
Minus a result set using EXCEPT operator:
SELECT * FROM table1
EXCEPT
SELECT * FROM table2;
Get intersection of the result sets of two queries:
SELECT * FROM table1
INTERSECT
SELECT * FROM table2;
Modifying data
Insert a new row into a table:
INSERT INTO table(column1,column2,...)
VALUES(value_1,value_2,...);
Insert multiple rows into a table:
INSERT INTO table_name(column1,column2,...)
VALUES(value_1,value_2,...),
(value_1,value_2,...),
(value_1,value_2,...)...
Update data for all rows:
UPDATE table_name
SET column_1 = value_1,
...;
Update data for a set of rows specified by a condition in the WHERE clause.
UPDATE table
SET column_1 = value_1,
...
WHERE condition;
Delete all rows of a table:
DELETE FROM table_name;
Delete specific rows based on a condition:
DELETE FROM table_name
WHERE condition;
Performance
Show the query plan for a query:
EXPLAIN query;
Show and execute the query plan for a query:
EXPLAIN ANALYZE query;
Collect statistics:
ANALYZE table_name;