MySQL存儲過程與if語句

Question

我在MySQL中有以下存儲過程

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;

該存儲的過程有2個（IN）輸入， kid_Id （整數）和received_Date （日期），並能正常工作。

問題：我想要的是，如果received_Date為NULL那么我想查看所有日期，這可能嗎？

換句話說：

在AND rewards.received_at = received_Date如果我通過應只工作received_Date否則返回所有日期。

Answer 1

嘗試這個。 如果received_Date is null則在where clause使用OR運算符獲取所有行

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;