GNU/Linux man pages
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Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 2.1AS(Slurm) |
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delete(l) |
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DELETE − Removes rows from a table
DELETE FROM [ ONLY ] table [ WHERE condition ]
INPUTS
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table |
The name of an existing table. |
condition
This is an SQL selection query which returns the rows which are to be deleted.
Refer to the SELECT statement for further description of the WHERE clause.
OUTPUTS
DELETE count
Message returned if items are successfully deleted. The count is the number of rows deleted.
If count is 0, no rows were deleted.
DELETE removes rows which satisfy the WHERE clause from the specified table.
If the condition (WHERE clause) is absent, the effect is to delete all rows in the table. The result is a valid, but empty table.
Tip: TRUNCATE [truncate(l)] is a Postgres extension which provides a faster mechanism to remove all rows from a table.
By default DELETE will delete tuples in the table specified and all its sub-tables. If you wish to only update the specific table mentioned, you should use the ONLY clause.
You must have write access to the table in order to modify it, as well as read access to any table whose values are read in the condition.
Remove all films but musicals:
DELETE FROM
films WHERE kind <> ’Musical’;
SELECT * FROM films;
code | title |
did | date_prod | kind | len
-------+---------------------------+-----+------------+---------+-------
UA501 | West Side Story | 105 | 1961-01-03 | Musical | 02:32
TC901 | The King and I | 109 | 1956-08-11 | Musical | 02:13
WD101 | Bed Knobs and Broomsticks | 111 | | Musical | 01:57
(3 rows)
Clear the table films:
DELETE FROM
films;
SELECT * FROM films;
code | title |
did | date_prod | kind | len
------+-------+-----+-----------+------+-----
(0 rows)
SQL92
SQL92 allows a positioned DELETE statement:
DELETE FROM
table WHERE
CURRENT OF cursor
where cursor identifies an open cursor. Interactive cursors in Postgres are read-only.
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delete(l) | |