Question

I want delete ROW(s) in two database table(mysql) with sql JOIN but get error:

This is my sql code:

table_1.id => have one row with id 3
table_2.rela => have three row with real 3 (sometimes number row table_2.rela join with table_1.id is 1 or 5 or 2 or …)

  //$id = $this->input->post('id');
    $id = '3';
        $this->db->query("
        DELETE *
        FROM table_1
        JOIN  table_2
           ON table_1.id = table_2.rela
        WHERE table_1.id = '.$id.'");

With above query i get this error:

A Database Error Occurred
Error Number: 1064

You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use
near ‘* FROM table_1 JOIN table_2 ON table_1.’ at line 1

DELETE * FROM table_1 JOIN table_2 ON table_1.id = table_2.rela WHERE
table_1.id = ‘.3.’

How is fix it?

Answer 1

You cannot use the wildcard after the DELETE. You have to specify the table from which you want to delete records. Your query should be something like:

$this->db->query("
        DELETE table_1, table_2
        FROM table_1
        JOIN  table_2
           ON table_1.id = table_2.rela
        WHERE table_1.id = ".floor($id));

Assuming that the ids are int. This also removes invalid characters if the $id may come from user input.