c# - rank records according to vendors having most sales(Quantity*Price) -

mine event management related website.. on admin side need following : vendorname , vendorphoto, vendorphone , vendoremail , servicetype(serviceid) based on rankin of sales(quantity*price) displayed in eventitem table , i.e. :

a vendor a(serviceid : 1 , service.name:florist) has couple of vendoritems in table vendoritem(i.e. product table) , other vendors have entries in table vendoritem . when user registers event choose quantity , product(i.e. vendoritem) of vendor.

then query should check amongst vendors of particular type(e.g. : florist,etc) , has sales(top 3)/

this query have tried far, not able required results , confused in how calculate value quantity*product ?

  select        top (3) tblvendor.vendorid, tblvendor.name, tblvendor.email, tblvendor.phone, tblvendor.address, tblvendor.username, tblvendor.password, tblvendor.serviceid,                           tblvendor.isactive, tblvendor.photo, tbleventitem.quantity, tbleventitem.price            tbleventitem cross join                          tblvendor inner join                          tbleventservice on tbleventservice.vendorid = tblvendor.vendorid        (tbleventservice.vendorid = 7) order isnull(tbleventitem.quantity, 0) * isnull(tbleventitem.price, 0) desc 

select top 3 tbleventitem.quantity*tbleventitem.price 'sales',              tbleventitem.vendoritemid,              tblvendor.name,              tblvendor.email,              tblvendor.phone,              tblvendor.photo  tbleventservice  inner join tbleventitem on             tbleventservice.eventserviceid = tbleventitem.eventserviceid  inner join tblvendor on             tbleventservice.vendorid = tblvendor.vendorid  tbleventservice.serviceid = @s_id  order 'sales' desc 

this query magic .

here make column multiplying 2 columns : tbleventitem.quantity*tbleventitem.price , taking column sales .

other selections basic inner joins per requirements in select query .

the order 'sales' desc give top 3 vendors max sales!