how to use joining with LinQ To Entity

Question

I have this code

    var value = (from dc in _context.ContractDetails
                   where dc.EmployeeID == id
                    select dc.Amount);
    return value;
}

is it acceptable to do Value.Sum();

Answer 1

You want to return the sum it looks like. Instead of having query be a decimal, just let it be what it wants (var, it's really IEnumerable<decimal>). Then you can return an aggregate on that. Sum for example

var query = from emp in Employees
            join cd in ContractDetails
            on emp.EmployeeID equals cd.EmployeeID
            where cd.EmployeeID == id
            select cd.Amount;
return query.Sum();

If this is all it does, then I also feel like you don't need to join at all, and it would be simpler to do

var query = from cd in ContractDetails
            where cd.EmployeeID == id
            select cd.Amount;
return query.Sum();

... unless you were using the join to test for the existence of an employee in the Employee table as a condition.