DELETE (SQL)

This document covers the following topics:

Belongs to Function Group: Database Access and Update

See also DELETE - SQL in the Natural for Db2 part of the Database Management System Interfaces documentation:

DELETE (SQL) Usage

The SQL DELETE statement is used to delete either rows in a table without using a cursor ("searched" DELETE) or rows in a table to which a cursor is positioned ("positioned" DELETE).

Two different structures are possible.

Syntax 1 - Searched DELETE

The "searched" DELETE statement is a stand-alone statement not related to any SELECT statement. With a single statement you can delete zero, one, multiple or all rows of a table. The rows to be deleted are determined by a search-condition that is applied to the table. Optionally, the table name can be assigned a correlation-name.

Note
The number of rows that have actually been deleted with a "searched" DELETE can be ascertained by using the system variable *ROWCOUNT; see System Variables documentation.

Common Set Syntax:

DELETE FROM table-name [correlation-name] [WHERE search-condition]

Extended Set Syntax:

DELETE FROM table-name [period-clause] [correlation-name]
[include-columns [SET assignment-clause]]
[WHERE search-condition]
[FETCH FIRST row-limit]

WITH

RR
RS
CS

[SKIP LOCKED DATA] [QUERYNO integer]

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

Syntax Element Description:

Syntax Element Description
FROM table-name
FROM Clause:

Specifies the table from which the rows are to be deleted.
period-clause
Period Clause:

Specifies that a period clause applies to the target of the update operation. For further information, see Period Clause in the section Basic Syntactical Items.

correlation-name
Correlation Name:

Optional. The table name can be assigned a correlation-name.

include-columns
Include Columns Clause:

Optional. Specifies a set of columns that are included, along with the columns of table-name, in the result table of the DELETE statement, when it is nested in the FROM clause of a SELECT statement.

For further details, see include-columns.

SET assignment-clause
SET Assignment Clause:

Introduces the assignment of values to the included columns of the include-columns clause. See assignment clause of SQL UPDATE statement.

WHERE search-condition
WHERE Clause:

Specifies the selection criteria for the rows to be deleted.

If no WHERE clause is specified, the entire table is deleted.

FETCH FIRST
FETCH FIRST Clause:

Limits the effects of the DELETE statement to a subset of qualifying rows.

It corresponds to the FETCH FIRST clause of the SELECT statement described in FETCH FIRST row-limit.

WITH
WITH Isolation Level Clause:

Enables the explicit specification of the isolation level used when locating the row to be deleted.

This clause belongs to the SQL Extended Set.

CS Cursor Stability
RR Repeatable Read
RS Read Stability
SKIP LOCKED DATA
SKIP LOCKED DATA Clause:

Specifies that rows are skipped when incompatible locks are held on the row by other transactions.

QUERYNO integer
QUERYNO Clause:

This clause belongs to the SQL Extended Set.

This clause explicitly specifies the number to be used in EXPLAIN output and trace records for this statement. The number is used as QUERYNO column in the PLAN_TABLE for the rows that contain information on this statement.

Syntax 2 - Positioned DELETE

The "positioned" DELETE statement always refers to a cursor within a database loop. Therefore the table referenced by a positioned DELETE statement must be the same as the one referenced by the corresponding SELECT statement, otherwise an error message is returned. A positioned DELETE cannot be used with a non-cursor selection.

The functionality of the positioned DELETE statement corresponds to that of the "native" Natural DELETE statement.

Common Set Syntax:

DELETE FROM table-name WHERE CURRENT OF CURSOR [(r)]

Extended Set Syntax:

DELETE FROM table-name WHERE CURRENT OF CURSOR [(r)]

FOR ROW

[:]host-variable
integer

OF ROWSET

For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.

Syntax Element Description:

Syntax Element Description
FROM table-name WHERE CURRENT OF CURSOR
FROM Clause:

This clause specifies the table from which the rows are to be deleted.
(r)
Statement Reference:

The (r) notation is used to reference the statement which was used to select the row to be deleted. If no statement reference is specified, the DELETE statement is related to the innermost active processing loop in which a database record was selected.

FOR ROW ... OF ROWSET
FOR ROW … OF ROWSET Clause:

This clause belongs to the SQL Extended Set.

The optional FOR ROW ... OF ROWSET clause for positioned SQL DELETE statements specifies which row of the current rowset has to be deleted. It should only be specified if the DELETE statement is related to a SELECT statement which uses rowset positioning and which has column arrays in its INTO clause, see into-clause. If this clause is omitted, all rows of the current rowset are deleted.

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