Update Table Variable From Another Table

I need to update a table variable with a sum from another table. Something like this:


DECLARE @MyTableVariable Table

(

Location varchar(10),

ItemNumber Varchar(10)

Amount money,

Quantity int

)



UPDATE @MyTableVariable

SET Quantity =( SELECT SUM(Quantity)

FROM myTable

WHERE @MyTableVariable.[Location] = myTable.[Location]

and

@MyTableVariable.[ItemNumber] = myTable.[ItemNumber] )

The where clause does not work though. Is there a way to do this?