sql内连接删除

Question

I have tow tables

tests_sub ,tests_sub_sub

and tests_sub.id = tests_sub_sub.id

so i want to delete data from both tables with one

sql query

I used the following inner join

DELETE tests_sub, tests_sub_sub FROM tests_sub
INNER JOIN tests_sub_sub ON tests_sub_sub.id = tests_sub.id
WHERE tests_sub.id = 10

the query works ok only if both tables have entries for the tests_sub.id... ( if tests_sub_sub has no entry for test_sub.id = 10 ... although the table tests_sub has entries for that id no rows are affected ... please suggest some tips....

Answer 1

use LEFT JOIN .

DELETE tests_sub, tests_sub_sub 
FROM   tests_sub
       LEFT JOIN tests_sub_sub 
          ON tests_sub_sub.id = tests_sub.id
WHERE  tests_sub.id = 10