Date: 12/28/05 (MySQL Communtiy)    Keywords: no keywords

I want to merge these three queries into one query (and then add more) but I cant seem to wrap my head arround combining the first two.

ultimately I want to combine the 3 subtotals into one value.

Query1
SELECT invoice_number, sum(((TIME_TO_SEC(end_time) - TIME_TO_SEC(start_time))/3600) * rate) AS subtotal
FROM invoice_items
WHERE office_id='$office_id' AND service_type!='225'
GROUP BY invoice_number
ORDER BY invoice_number

Query2
SELECT invoice_number, sum((1) * rate) AS subtotal
FROM invoice_items
WHERE office_id='$office_id' AND service_type='225'
GROUP BY invoice_number
ORDER BY invoice_number

Query3
SELECT invoice_number, sum((mileage*mileage_rate)+groceries_value-discount_value) AS subtotal
FROM invoice_main
WHERE office_id='$office_id'
GROUP BY invoice_number
ORDER BY invoice_number

Source: http://www.livejournal.com/community/mysql/79721.html