LOOP#
Synopsis#
[label :] LOOP
statements
END LOOP
Description#
The LOOP statement is an optional construct in SQL
routines to allow processing of a block of statements
repeatedly.
The block of statements is processed until an explicit use of LEAVE causes
processing to exit the loop. If processing reaches END LOOP, another iteration
of processing from the beginning starts. LEAVE statements are typically
wrapped in an IF statement that declares a condition to stop the loop.
The optional label before the LOOP keyword can be used to name the
block.
Examples#
The following function counts up to 100 with a step size step in a loop
starting from the start value start_value, and returns the number of
incremental steps in the loop to get to a value of 100 or higher:
FUNCTION to_one_hundred(start_value int, step int)
RETURNS int
BEGIN
DECLARE count int DEFAULT 0;
DECLARE current int DEFAULT 0;
SET current = start_value;
abc: LOOP
IF current >= 100 THEN
LEAVE abc;
END IF;
SET count = count + 1;
SET current = current + step;
END LOOP;
RETURN count;
END
Example invocations:
SELECT to_one_hundred(90, 1); --10
SELECT to_one_hundred(0, 5); --20
SELECT to_one_hundred(12, 3); -- 30
Further examples of varying complexity that cover usage of the LOOP statement
in combination with other statements are available in the SQL routines examples
documentation.