我的mysql存储过程有什么问题？答案

【问题标题】：What is wrong with my mysql stored procedure?我的mysql存储过程有什么问题？
【发布时间】：2019-09-02 07:02:49
【问题描述】：

我有一个存储过程来检查表中是否已经存在新条目。如果存在，则不会发生插入。当我运行它时，有一个错误

DROP PROCEDURE IF EXISTS AddPriority2;
DELIMITER $$

CREATE PROCEDURE AddPriority2
(
    IN strName VARCHAR(100),
    OUT itExists INT
)
BEGIN
DECLARE 
SELECT COUNT(Id) INTO itExists
FROM priorities
WHERE Name = strName AND StatId = 1;

IF(itExists = 0) THEN
INSERT INTO priorities
(
    NAME,
    StatId
)
VALUES
(
    strName,
    1
);
END IF;
END

这是错误

Query: CREATE PROCEDURE AddPriority2 ( IN strName VARCHAR(100), OUT itExists INT ) BEGIN DECLARE SELECT COUNT(Id) INTO itExists FROM pr...

Error Code: 1064
You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'SELECT COUNT(Id) INTO itExists
FROM priorities
WHERE Name = strName AND StatId =' at line 8

【问题讨论】：

标签： mysql if-statement stored-procedures

【解决方案1】：

1) 你不能声明一个 select 语句 - 一个声明必须是一个变量..(我不会为此使用输出参数) 2) 或者你可以使用 exists 代替

if not exists (select 1 from priorities WHERE Name = strName AND StatId = 1) then
   insert...
end if;

【讨论】：