c# - Combine the results of a sql query together in one result -

i have application(c#) manages stock level every storage unit. want complete overview of stock level of every product every stock unit together.

for example have 50 apples (productid 1) in unit 1 , 25 in unit 2 , use query:

 select stocklevel     supply    productid = '1'

and put result in textbox gives me first stocklevel of 50 apples , not 75.

is there way can combine these results in easy way?

if want combine, want aggregate function, sum in case:

 select sum(stocklevel)    supply   productid = '1'

and apples being summed up: 75 50 + 25

WIKI