MySQL存储过程与if语句

Question

我在MySQL中有以下存储过程

SELECT *
    FROM rewards
        LEFT JOIN tasks
        ON tasks.id = rewards.task_id
        AND rewards.received_at = received_Date
    WHERE tasks.kid_id = kid_Id
    ORDER BY tasks.id ASC;

该存储的过程有2个（IN）输入， kid_Id （整数）和received_Date （日期），并能正常工作。

问题：我想要的是，如果received_Date为NULL那么我想查看所有日期，这可能吗？

换句话说：

在AND rewards.received_at = received_Date如果我通过应只工作received_Date否则返回所有日期。

Answer 1

尝试这个。 如果received_Date is null则在where clause使用OR运算符获取所有行

SELECT *
    FROM rewards
        LEFT JOIN tasks
        ON tasks.id = rewards.task_id
                WHERE tasks.kid_id = kid_Id 
                AND (rewards.received_at = received_Date or received_Date = 0) 
    ORDER BY tasks.id ASC;