Conditional insert

Databases
1

I have

CREATE TABLE Persons (
     name varchar(255) NOT NULL UNIQUE
);

How do I run an INSERT query only if the name is UNIQUE?

2

You would just attempt to run the insert query. If the value doesn’t exist, a row will be inserted. If the value already exists, the query will produce a duplicate index/unique constraint error number that you can test for in your application code.

2 Likes
3

@mabismad has the correct answer

however, you could also just use MySQL’s INSERT IGNORE syntax, or use REPLACE instead of INSERT – assuming you’re using MySQL, which you never mentioned

1 Like
5

thanks

6

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