mysql如果不存在

本文介绍了mysql如果不存在的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我来自MSSQL，现在使用Mysql，这可能很简单，但如果不存在语句，如何执行。谢谢

I am coming from MSSQL, and now using Mysql, this may be a easy one but how do you execute a if not exist statement. thanks

IF NOT EXISTS(SELECT * from users WHERE Username = spUsername) BEGIN INSERT into users(ID,Username,Password,Email,Birthdate,DateJoin) VALUES(UUID(),spUsername,spPassword,spEmail,spBirthDate,NOW()); END

推荐答案

我不是数据库专家任何方法，但这就是我这样做。

Im not a database expert by any means but this is how I do it.

www.somethinghitme/2010/05/06/mysql-stored-procedures-if-not-exists/

DECLARE SomeId int; DECLARE CheckExists int; SET CheckExists = 0; SELECT 1 INTO CheckExists from lookup_table WHERE someField = in_SomeParam LIMIT 1; IF (CheckExists > 0) THEN SELECT id INTO SomeId FROM lookup_table WHERE someField = in_SomeParam; ELSE INSERT INTO lookup_table (someField ) VALUES(in_SomeParam); SELECT SomeId = LAST_INSERT_ID(); END IF;