Update & Join?

[router]

Hello!
I want to update a table(t1) but only the rows what are in other table(t2). I try to do it, but i can.
If you try to use it (it's an example,of course):
UPDATE t1
SET t1.a='a'
WHERE t1.b=t2.c;
It won't work because, it don't know t2.
But if you try something like that:
UPDATE t1,t2
SET t1.a='a'
WHERE t1.b=t2.c;
It will be a syntax error.
Some idea?
Thanks in advance!! 🙂

Router

(Sorry for my english!)

[Lars_Berg]

update t1 set a = 'a'
where b in (select c from t2)

[router]

Thank for your help, but i try to do it and it doesn't work because in mysql it doesn't exit "sub-select" and "IN" only works to search in a constant expresion, no to search in a varaible expresion.
Thank you again!
Some idea?
Router

[Lars_Berg]

If you are using Mysql, my advice is to change to a real rdbms, one that supports basic SQL.

To solve this with Mysql, I think that you first need to select the values from t2 and build the delete statement dynamically in PHP.