how to check if a record not exist and then insert

Question

I mean that when I want to insert a record into MySQL, I first check if it exists.

This is usually used when dealing with user registration, I should check the username submitted whether or not has been registered. I do not want to use a unique index because I have a logical delete in my db.

I try to user select ... for update, but for data not exist, it doesn't work well.

Possible duplicate of: https://stackoverflow.com/questions/1361340/how-to-insert-if-not-exists-in-mysql — Jeppsen, Jul 12 '18 at 12:31
May be a duplicate of: https://stackoverflow.com/questions/3164505/mysql-insert-record-if-not-exists-in-table — gcourtet, Jul 12 '18 at 12:32

score 0 · Answer 1 · answered Jul 12 '18 at 13:38

0

For an example：

insert into user_table(id,user_name,deleted)
select 1,'new user name',0 from user_table where `user_name`<>'new user name' and deleted=0 limit 1;

answered Jul 12 '18 at 13:38

Joyson

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how to check if a record not exist and then insert

1 Answers1