How to select unique from multiple tables

Okay,

Here's my tables:

Table: husbands

-------------------

Column: sid

####################

Table: wives

-------------------

Column: sid

####################

Table: children

-------------------

Column: sid

I am trying to select the sid of all with say "4003".

I need to select the unique sid for all tables combined, then display it in php.

Wheres what I was thinking, but doesnt work:

<?php $sql = mysql_query("
SELECT sid
FROM husbands, wives
WHERE 
husbands.sid = wives.sid

");
while ($row = mysql_fetch_assoc($sql)){
echo "".$row['husbands.sid']." <br>";
}
?>

Try:

SELECT sid
FROM husbands INNER JOIN wives ON (husbands.sid = wives.sid)
        INNER JOIN children ON (husbands.sid = wives.sid)

I got this to work for me:

select * from husbands join wives using(sid) join children using(sid) where husbands.sid = 4003;

output with 2 children (see attachment)

[attachment deleted by admin]

There's nothing unique about that.

select * from husbands join wives using(sid) join children using(sid) where husbands.sid = 4003 group by husbands.sid;

select * from husbands join wives using(sid) join children using(sid) where husbands.sid = 4003 group by husbands.sid;

Nice job man! If you guys are curious I am coding a Family Tree project for a relative (free work).

Again, * is garbage with GROUP BY -- don't do that.