mysql - 如果值不存在则插入

Question

在我的数据库中，我有 tickets_users 将用户关联到工单。

如果还没有这个 users_id(例如用户 1444)，我想做一个 INSERT 检查 tickets_users type = 2 WHERE tickets_id = something(例如票号 455)；如果它已经存在什么都不做，否则

INSERT INTO tickets_users (tickets_id, users_id, type) VALUES (455, 1444, 2) 
WHERE tickets_id = 455

Answer 1

INSERT INTO tickets_users (tickets_id, users_id, type) 
select 455, 1444, 2 from  dual
WHERE not exists (select 1 from tickets_users where type = 2 and tickets_id = something)

试试这个

编辑:
添加多行

INSERT INTO tickets_users (tickets_id, users_id, type) 
select 455, 1444, 2 from  dual
WHERE not exists (select 1 from tickets_users where type = 2 and tickets_id = 455)
union all 
select 456, 1444, 2 from  dual
WHERE not exists (select 1 from tickets_users where type = 2 and tickets_id = 456)