mysql delete operation

Question

Hi,

is there a way to delete a relation only if it exists in the table? If not, Whats the best approach when deleting a relation in a table:

1. Check if the relation exists. If it does then delete. (2 operations)
2. Delete and catch the error if it didnt exist. (1 operation)

Thanks

Answer 1

I think you can do a subselect and choose which record you want to delete from that subselect, something like this

DELETE FROM target WHERE target_table.id IN (
  SELECT target_table.id INNER JOIN relation_table ON relation_table.target_table_id = target_table.id
)

where the subselect, using INNER JOIN will return records with relations =)

hope it helps! =)

Answer 2

DELETE FROM table WHERE id=30

will delete a row if it exists and will do nothing if it is not. No need for catching errors.

Answer 3

DELETE deletes a row only if it's exist. It doesn't throw an error if there is nothing to delete.