[引]MySQL帮助文档之Cursors游标

Simple cursors are supported inside stored procedures and functions.

The syntax is as in embedded SQL. Cursors are currently asensitive, read-only, and non-scrolling.

Asensitive means that the server may or may not make a copy of its result table.

Cursors must be declared before declaring handlers,

and variables and conditions must be declared before declaring either cursors or handlers.

Example:

CREATE PROCEDURE curdemo()

BEGIN

  DECLARE done INT DEFAULT 0;

  DECLARE a CHAR(16);

  DECLARE b,c INT;

  DECLARE cur1 CURSOR FOR SELECT id,data FROM test.t1;

  DECLARE cur2 CURSOR FOR SELECT i FROM test.t2;

  DECLARE CONTINUE HANDLER FOR SQLSTATE '02000' SET done = 1;

  OPEN cur1;

  OPEN cur2;

  REPEAT

    FETCH cur1 INTO a, b;

    FETCH cur2 INTO c;

    IF NOT done THEN

       IF b < c THEN

          INSERT INTO test.t3 VALUES (a,b);

       ELSE

          INSERT INTO test.t3 VALUES (a,c);

       END IF;

    END IF;

  UNTIL done END REPEAT;

  CLOSE cur1;

  CLOSE cur2;

END