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DELETE

Deletes rows from a table.

Syntax​

DELETE FROM [ONLY] <table> [[AS] <alias>]
      [WHERE <condition> ]

Description​

DELETE deletes rows that satisfy the WHERE clause from the specified table. If the WHERE clause is absent, the effect is to delete all rows in the table. The result is a valid, but empty table.

By default, DELETE will delete rows in the specified table and all its child tables. If you wish to delete only from the specific table mentioned, you must use the ONLY clause.

You can use sub-selects to delete rows in a table using information contained in other tables in the database.

You must have the DELETE privilege on the table to delete from it.

note

As the default, Relyt acquires an EXCLUSIVE lock on tables for DELETE operations on heap tables.

Parameters​

  • ONLY

    If specified, delete rows from the named table only. When not specified, any tables inheriting from the named table are also processed.

  • <table>

    The name of an existing table. You can specify the name with the schema qualification.

  • <alias>

    A substitute name for the target table. When an alias is provided, it completely hides the actual name of the table. For example, given DELETE FROM foo AS f, the remainder of the DELETE statement must refer to this table as f not foo.

  • <condition>

    An expression returning a value of type boolean, which determines the rows that are to be deleted.

Outputs​

On successful completion, a DELETE command returns a command tag of the form

DELETE <count>

The <count> is the number of rows deleted. If count is 0, no rows were deleted by the query (this is not considered an error).

Examples​

Delete all films but musicals:

DELETE FROM films WHERE kind <> 'Musical';

Clear the table films:

DELETE FROM films;

SQL standard compatibility​

This command conforms to the SQL standard.