How to SUM and SUBTRACT using SQL?

Question

I am using MySQL and I have two tables:

master_table

• ORDERNO
• ITEM
• QTY

stock_bal

Answer 1

I'm not sure exactly what you want, but I think it's along the lines of:

SELECT `Item`, `qty`-`BAL_QTY` as `qty` FROM ((SELECT Item, SUM(`QTY`) as qty FROM `master_table` GROUP BY `ITEM`) as A NATURAL JOIN `stock_table`) as B