Why am I getting "Unknown Column" error? - sql

Question

The exact error I am getting is: "Unknown column 'trans_paid' in 'where clause'"
My query ($from_date and $to_date are correctly formatted):
SELECT
o.order_id,
o.order_po_no,
o.order_ship_date,
acct.acct_company,
SUM( ROUND( i.item_qty * i.item_price, 2 ) ) AS item_amount, (
SELECT SUM( trans_amount )
FROM transactions
WHERE order_id = o.order_id
AND trans_pending =0
AND trans_date >= '$from_date'
AND trans_date <= '$to_date'
) AS trans_paid
FROM orders AS o
INNER JOIN accounts AS acct ON o.acct_id = acct.acct_id
INNER JOIN items AS i ON o.order_id = i.order_id
WHERE (o.order_status =7 or o.order_status = 4)
AND trans_paid IS NOT NULL
AND acct.is_wholesale =1
AND acct.acct_company LIKE '%".$_POST['company']."%'
GROUP BY o.order_id

Answer 1

You can't reference aliased columns in the SELECT cause from the WHERE clause. You'll have to wrap it in a subquery if you want to filter on it.

Answer 2

Standard SQL doesn't allow you to refer to aggregate columns in the WHERE clause. You need to move the trans_paid condition to a HAVING clause to make it work.
Change
WHERE (o.order_status =7 or o.order_status = 4)
AND trans_paid IS NOT NULL
AND acct.is_wholesale =1
AND acct.acct_company LIKE '%".$_POST['company']."%'
GROUP BY o.order_id
to
WHERE (o.order_status =7 or o.order_status = 4)
AND acct.is_wholesale =1
AND acct.acct_company LIKE '%".$_POST['company']."%'
GROUP BY o.order_id
HAVING trans_paid IS NOT NULL

Answer 3

An alias name to be used in the Where clause has to be declared in the FROM clause...You simply renamed a column not actually rename an object such as a table.

Answer 4

use this query:
SELECT
o.order_id,
o.order_po_no,
o.order_ship_date,
acct.acct_company,
SUM( ROUND( i.item_qty * i.item_price, 2 ) ) AS item_amount,
trans_paid
FROM orders AS o
LEFT JOIN
(SELECT SUM( trans_amount ) AS trans_paid
FROM
WHERE trans_pending =0
AND trans_date >= '$from_date'
AND trans_date <= '$to_date'
) temp
USING order_id
INNER JOIN accounts AS acct ON o.acct_id = acct.acct_id
INNER JOIN items AS i ON o.order_id = i.order_id
WHERE (o.order_status =7 or o.order_status = 4)
AND trans_paid IS NOT NULL
AND acct.is_wholesale =1
AND acct.acct_company LIKE '%".$_POST['company']."%'
GROUP BY o.order_id