Mysql存储过程忽略参数和WHERE条件

Question

我有以下效果很好的:

SET @param = '%string%';

SELECT *
FROM tbl
WHERE IF(@param IS NOT NULL, LIKE @param, TRUE);

但是当我更改为:

DELIMITER //
CREATE PROCEDURE test(IN param VARCHAR(255))
BEGIN
SET @param = param;

SELECT *
FROM tbl
WHERE IF(@param IS NOT NULL, LIKE @param, TRUE);
END //
DELIMITER ;

CALL test('%string%');

所有行都会返回，就像没有传入参数一样。

我认为 MySQL 存在一些我遗漏的限制或限制？

Answer 1

不确定，但请尝试使用准备好的声明

DELIMITER //
CREATE PROCEDURE test(IN param VARCHAR(255))
BEGIN
SET @param = param;

SET @q = CONCAT("SELECT *
FROM tbl
WHERE IF(",@param," IS NOT NULL, LIKE ",@param,", TRUE)");

PREPARE stmt FROM @q;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

END //
DELIMITER ;