相关疑难解决方法(0)

我试图在存储过程中使用变量作为表名,并将其用作字符串文字而不是实际的表名.为什么是这样？还有另一种方法我应该这样做(除了在PHP中这样做)？

DROP PROCEDURE IF EXISTS settonull;

DELIMITER //

CREATE PROCEDURE settonull()
BEGIN
  DECLARE done INT DEFAULT FALSE;
  DECLARE _tablename VARCHAR(255);
  DECLARE _columnname VARCHAR(255);
  DECLARE cur1 CURSOR FOR SELECT CONCAT(TABLE_SCHEMA, '.', TABLE_NAME) AS table_name, COLUMN_NAME AS column_name FROM information_schema.COLUMNS WHERE IS_NULLABLE = 'YES' AND TABLE_SCHEMA = 'blip_notify' AND table_name = 'notify_queue' LIMIT 1;

  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

  OPEN cur1;

  read_loop: LOOP
    FETCH cur1 INTO _tablename, _columnname;

    IF done THEN
      LEAVE read_loop;
    END IF;

    UPDATE _tablename …