mysql - 存储过程不会返回 OUT var

Question

我对存储过程很感兴趣，下面的内容让我感到困惑。看来 @Status 变量没有被设置？

当我调用查询时，它运行良好，但返回 null。我正在使用以下方式调用:

call new_customer1('Someone@someemail.com', @Status);
SELECT @Status;

SP 查询如下

CREATE PROCEDURE new_customer1(
IN CusEmail VARCHAR(75),
OUT Status TINYINT(2)
)
BEGIN
IF EXISTS (SELECT Email FROM customers WHERE Email = @CusEmail)
THEN SET @Status = 1;
ELSE
# Perform inssert
SET @Status = 0;
END IF;
END $$

Answer 1

架构

create table customers
(  id int auto_increment primary key,
   email varchar(100) not null
);

insert customers (email) values ('trump@trump.com');

存储过程

drop procedure if exists new_customer1;
DELIMITER $$
CREATE PROCEDURE new_customer1(IN CusEmail VARCHAR(75), OUT NewStatus TINYINT(2))
BEGIN
    IF EXISTS (SELECT Email FROM customers WHERE Email = CusEmail) THEN 
        SET NewStatus = 1;
    ELSE
        SET NewStatus = 0;
    END IF;
END
$$
DELIMITER ;

测试

call new_customer1('notthere',@theOut);
select @theOut; -- 0
call new_customer1('trump@trump.com',@theOut);
select @theOut; -- 1