过程中的光标不返回任何值-CursorinProceduredoesnotreturnanyvalues

You have to add something like this in order to end your loop:

你必须添加这样的东西才能结束你的循环:

DECLARE CONTINUE HANDLER FOR NOT FOUND SET ...;

See example in the documentation.. E.g. ...

请参阅文档中的示例..例如...

DROP PROCEDURE IF EXISTS `spCheckoutsCleanup`;
CREATE PROCEDURE `spCheckoutsCleanup` ()
  SQL SECURITY INVOKER
BEGIN
    DECLARE done INT DEFAULT FALSE;
    DECLARE `t` VARCHAR(64);
    DECLARE `ch` CURSOR FOR SELECT `unid` FROM `Checkouts`;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET dOne= TRUE;

    OPEN `ch`;

    drop_tables: LOOP
        FETCH `ch` INTO `t`;
        IF done THEN
           LEAVE drop_tables;
        END IF;
        DROP TABLE IF EXISTS `t`;
    END LOOP;

    CLOSE `ch`;
    TRUNCATE TABLE `Checkouts`;
END

Otherwise you will get an error once you reached the end of your cursor.

否则,一旦到达光标的末尾,就会出现错误。

I got it working with this:

我得到了它:

DROP PROCEDURE IF EXISTS `spCheckoutsCleanup`;
CREATE PROCEDURE `spCheckoutsCleanup` ()
  SQL SECURITY INVOKER
BEGIN
    DECLARE done int DEFAULT 0;
    DECLARE t CHAR(64);
    DECLARE ch CURSOR FOR SELECT `unid` FROM `Checkouts`;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET dOne= 1;
    OPEN ch;

    drop_table: LOOP
        FETCH ch INTO t;
        IF dOne= 1 THEN
            LEAVE drop_table;
        END IF;
        SET @sql := CONCAT('DROP TABLE IF EXISTS `', t, '`'); 
        PREPARE dropt FROM @sql; 
        EXECUTE dropt;
    END LOOP;

    CLOSE ch;
    TRUNCATE TABLE `Checkouts`;
END;
CALL spCheckoutsCleanup;