Hello friends,
Today, waiting for the saturday, we talk about a simple thing that you really should know about the UPDATE statement.
How many times have you seen updates done like this?
UPDATE ORDRIG
SET
NeatPrice = Price * (100-PercDiscount)/100,
total = NeatPrice * Qty
where
id = XX
Notice that the result of the second field depends on the result of the first one.
So in this case order matters.
How does SQL Server behave in this case?
Seems difficult but it is more easy than you could image!
Just learn this easy rule:
Of course you can tray by yourself doing this simple update:
CREATETABLE #ORDRIG(ID INTIDENTITY(1,1), PRICE FLOAT, NETPRICE FLOAT)
INSERTINTO #ORDRIG(PRICE,NETPRICE)VALUES (0,0)
UPDATE #ORDRIG SET PRICE = 5, NETPRICE = PRICE
SELECT*FROM #ORDRIG
Et voilà!
That's all for today
I wish you a great saturday!
Luca
