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Synopsis

[label :] WHILE condition DO
  statements
END WHILE

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Description

The WHILE statement is an optional construct in SQL routines to allow processing of a block of statements as long as a condition is met. The condition is validated as a first step of each iteration.

The expression that defines the condition is evaluated at least once. If the result is true, processing moves to DO, through following statements and back to WHILE and the condition. If the result is false, processing moves to END WHILE and continues with the next statement in the function.

The optional label before the WHILE keyword can be used to name the block.

Note that a WHILE statement is very similar, with the difference that for REPEAT the statements are processed at least once, and for WHILE blocks the statements might not be processed at all.

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Examples

WHILE p > 1 DO
  SET r = r * n;
  SET p = p - 1;
END WHILE;

Further examples of varying complexity that cover usage of the WHILE statement in combination with other statements are available in the SQL routines examples documentation.

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See also

SET