mysql - 如果数据库中不存在名字，它应该打印 smessage 但它会处于其他条件并插入

Question

CREATE DEFINER=`root`@`localhost` PROCEDURE `AddStudent`(in Firstname varchar(50)
,in Lastname varchar(50)
,in email varchar(50)
,out smessage varchar(500) )
BEGIN

SELECT first_name FROM web_student_tracker.student where first_name in (Firstname);

if Firstname=NULL then set smessage="Name not exsists";

else 

insert into student(first_name, last_name, email) values(Firstname,Lastname,email);


END IF;

结尾

标签： mysql

Answer 1

它必须是 null not = null。

if Firstname is NULL then set smessage="Name not exsists";