I did that in my own app but had to switch back to the stock in hand field because as time went by and the DB started to grow the calculation was more and more slow, also I had the need to calculate several items at once and that made the query much more slower than it is just retrieving the field.

What I did (with SQL Server 2000) was to create a trigger that updates the quantity on hand field every time it's needed.

HTH,

Enmanuel

>I have an inventory app, want to switch the back-end to MySQL, someone suggested me not to use calculated fields (eg: stock_OnHand) and replaced them with calculation by the fly.
>
>(I have stock_OnHand field to record the balance, while his idea is throw away this field, just keep the transactions, anytime need it, calculated them with SQL statement).
>
>I'm not sure about this, before I do a big change to my app, I would like to ask for second opinion, is this the way to do with MySQL?
>
>regards,
>
>Jerry