MYSQL update into select 3 tables

Question

I use this query (insert into select 3 tables) to insert my rows in the mysql table.

"INSERT INTO test (catid_1, descat_1, catid_2, descat_2, id_user, user)
 SELECT '$_POST[cat_1]',t1.desc AS descat_1, '$_POST[cat_2]', t2.desc AS descat_2, 
 $_POST[id_user]',t3.user FROM t1, t2, t3 
 WHERE t1.idcat_1='$_POST[cat_1]' and t2.idcat_2='$_POST[cat_2]' 
 and t3.id_user='$_POST[id_user]'";

Now I'd like to use the same logic to UPDATE my rows (update into select 3 table) in the mysql table.

tables structure

t1
`idcat_1` int(11) NOT NULL AUTO_INCREMENT,
`desc` varchar(100) NOT NULL,
PRIMARY KEY (`idcat_1`)

t2
`idcat_2` int(11) NOT NULL AUTO_INCREMENT,
`idcat_1` int(11) NOT NULL,
`desc` varchar(100) NOT NULL,
PRIMARY KEY (`idcat_2`)

t3
`id_user` int(11) NOT NULL AUTO_INCREMENT,
`user` varchar(40) NOT NULL,
PRIMARY KEY (`id_user`)

Is it possible to do?

Thanks

Answer 1

Like this:

UPDATE test AS t
INNER JOIN t1 ON -- join conditon
INNER JOIN t2 ON ...
INNER JOIN t3 ON ... 
SET t.catid_1 = '$_POST[cat_1]',
    t.descat_1 = t1.desc,
    ....
 WHERE t1.idcat_1='$_POST[cat_1]' 
   and t2.idcat_2='$_POST[cat_2]' 
   and t3.id_user='$_POST[id_user]'

It is not clear how the four tables are joined, you will need to supply the join condition for each JOIN .

---

Update 1

From the tables' structures that you just posted in your updated question, it seems like neither of the three tables test , t1 nor t2 related to the table t3 by any keys. In this key you didn't need to join with this table t3 and only join the tables test , t1 and t2 . Assuming that:

• test relates to t1 with test.catid_1 = t1.idcat_1 .
• t1 relates to t2 with t1.idcat_1 = t2.idcat_1 .

Like this:

UPDATE test AS t
INNER JOIN t1 ON t.catid_1 = t1.idcat_1
INNER JOIN t2 ON t1.idcat_1 = t2.idcat_1
SET t.catid_1 = '$_POST[cat_1]',
    t.descat_1 = t1.desc,
    ....
 WHERE t1.idcat_1='$_POST[cat_1]' 
   and t2.idcat_2='$_POST[cat_2]'