Question

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mysql getting last_insert_id() in a trigger

I have MySQL TRIGGER firing AFTER INSERT ON a table (my_table).

I wish to store the PRIMARY_KEY of the row effected by the TRIGGER in a variable using:

SET  @user_id =  LAST_INSERT_ID();

Which is backed by this stackoverflow link. And seems to be working.

However, each time it stores the value as 0.

From this stackoverflow link, I believe this is due to the fact that my_table is set to AUTO_INCREMENT.

SET  @user_id =  LAST_INSERT_ID();

What is the best practice to overcome this?

Answer 1

The LAST_INSERT_ID() function returns only autogenerated ID values. If you generated ID itself, then LAST_INSERT_ID() won’t return it.

Also, trigger works in another session. But LAST_INSERT_ID() works only for current session – where new ID was inserted, e.g. –

-- NULL means that ID will be generated by server
INSERT INTO table1(id) VALUES(NULL);
SELECT LAST_INSERT_ID();
> 1