Question

I Have 2 tables with this info

tabsell

SellId |      ItemId     
1      |        2      
2      |        3   
3      |        2     
4      |        3    
5      |        4   

tabitens (this table have alot of columns but i put only 2 for a example)

ItenId |      ItemName     
2      |        Iten2      
3      |        Iten3   
4      |        Iten4     
5      |        Iten5    

What im try to do is

Select FROM tabitens only if the SUM of the ItenId on tabsell is < 2

What is the right way to make the query?

Thanks!

Answer 1

you need to use LEFT JOIN on this so Items with no records (not been sold) on tableSell will also be shown on the list.

SELECT  a.ItemID, a.ItemName
FROM    tblItem a
        LEFT JOIN tblSell b
            ON a.ItemID = b.ItemID
GROUP BY a.ItemID, a.ItemName
HAVING COUNT(b.SellId) < 2  

COUNT is recommended to use than SUM because COUNT adds the number of rows while SUM adds the value of rows.