Question

This is not working for me:

UPDATE emails SET address = TRIM(address);

0 rows affected. ( Query took 0.2440 sec )

Why?

Thanks.

Answer 1

Maybe they didn’t actually need trimming. From the docs:

If you set a column to the value it currently has, MySQL notices this and does not update it.

UPDATE returns the number of rows that were actually changed.

In other words, they had no leading or trailing spaces.

If you really want to test this, use:

SELECT COUNT(*) FROM emails;
UPDATE emails SET address = CONCAT(' ', address);
UPDATE emails SET address = TRIM(address);

(that first one is to check the possibility of an empty table).