WHILE#
Примечание
Ниже приведена оригинальная документация Trino. Скоро мы ее переведем на русский язык и дополним полезными примерами.
Synopsis#
[label :] WHILE condition DO
statements
END WHILE
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.
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.