Available in: DSQL, ESQL, PSQL

Description

Changes values in a table (or in one or more tables underlying a view). The columns affected are specified in the SET clause; the rows affected may be limited by the WHERE and ROWS clauses.

Syntax

 UPDATE [TRANSACTION name] {tablename | viewname} [alias]
    SET col = newval [, col = newval ...]
    [WHERE {search-conditions | CURRENT OF cursorname}]
    [PLAN plan_items]
    [ORDER BY sort_items]
    [ROWS <m> [TO <n>]]

 <m>, <n> ::= Any expression evaluating to an integer.

Restrictions

• The TRANSACTION directive is only available in ESQL.
• WHERE CURRENT OF is only available in ESQL and PSQL.
• The PLAN, ORDER BY and ROWS clauses are not available in ESQL.
• New in 2.0: No column may be SET more than once in the same UPDATE statement.

back to top of page

ORDER BY

Available in: DSQL, PSQL

Added in: 2.0

Description

UPDATE now allows an ORDER BY clause. This only makes sense in combination with ROWS, but is also valid without it.

PLAN

Available in: DSQL, PSQL

Added in: 2.0

Description

UPDATE now allows a PLAN clause, so users can optimize the operation manually.

back to top of page

ROWS

Available in: DSQL, PSQL

Added in: 2.0

Description

Limits the amount of rows updated to a specified number or range.

Syntax

 ROWS <m> [TO <n>]

 <m>, <n> ::= Any expression evaluating to an integer.

With a single argument m, the update is limited to the first m rows of the dataset defined by the table or view and the optional WHERE and ORDER BY clauses.

Points to note:

• If m > the total number of rows in the dataset, the entire set is updated.
• If m = 0, no rows are updated.
• If m < 0, an error is raised.

With two arguments m and n, the update is limited to rows m to n inclusively. Row numbers are 1-based.

Points to note when using two arguments:

• If m > the total number of rows in the dataset, no rows are updated.
• If m lies within the set but n doesn't, the rows from m to the end of the set are updated.
• If m < 1 or n < 1, an error is raised.
• If n = m-1, no rows are updated.
• If n < m-1, an error is raised.

ROWS can also be used with the SELECT and DELETE statements.