SQL Delete Rows Based on Another Table

Question

This is probably very easy, but it\'s Monday morning. I have two tables:

Table1:

Field        | Type             | Null | Key | Default | Extra
id           


        

Answer 1

Something like this

delete from table1 where group in (select group from table2)

Answer 2

you can delete either table rows by using its alias in a simple join query like

delete a from table1 a,table2 b where a.uid=b.id and b.id=57;

here, you might specify either a or b to delete the corresponding table rows

Answer 3

Off the top of my head:

delete from Table1 where id in (select id from table1 inner join table2 on Table1.group = Table2.group)

I did this a little differently than other posters -- I think if there is a large number of rows on Table2 this might be better. Can someone please set me straight on that?

Answer 4

The nice solution is just writing the SQL as you say it yourself already:

DELETE FROM Table1
WHERE
  EXISTS(SELECT 1 FROM Table2 WHERE Table2.Group = Table1.Group)

Regards, Arno Brinkman

Answer 5

I think this is what you want:

DELETE FROM `table1`
WHERE `group` in (SELECT DISTINCT `group` FROM `table2`)

Answer 6

I think this way is faster:

DELETE FROM t1 USING table1 t1 INNER JOIN table2 t2 ON ( t1.group = t2.group );