JOIN tables, questions

[Mgccl]

I have read about join but still have many questions in mind.
Here are the list of them
suppose:
table1
id | username
table2
id| password
we join table 1 and table 2 where table1 id = table2 id....
so, the table we will have now(result table) should be
id| username| password
right?

Do we have to SELECT the 2 id fields in both tables or just need them after ON?

THEN how do we access the data in result table?

[Kudose]

$query = mysql_query("SELECT a.id, a.username, b.password FROM table1 a, table2 b ON a.id=b.id LIMIT 1");
$row = mysql_fetch_array($query);
$id = $row['id'];
$uname = $row['username'];
$pwd = $row['password'];

You need to declare that you want to select an ID, username and password to be returned. Using ON just defines what you are defining as the criteria for the match. MySQL will not return those fields by default.

[Mgccl]

how about if you want to put in a new where statement?
like WHERE username = mgccl
will it return a row that contain id, username and password as well?
because in the password database contains no username.
and you can join more table than one by putting more ON commands right?
As this question answered... All my project will be an ease because I can finally understant JOIN...

[Kudose]

If you add a WHERE clause, it will still return the SELECT values and only the SELECT values.

Just add it after the ON and before LIMIT