Question

I’m trying to execute parameterized SQLCommand, which should return 1 value. Instead, it return an empty set, no exception is thrown, the program just keeps going.

This is the query:

SELECT SUM(s.cost) AS cost
FROM Spending s JOIN Date d ON s.dateID = d.dateID 
    JOIN [Service category] sc ON s.[service categoryID] = sc.[service categoryID]
WHERE sc.category1 = 'Phone' AND s.personID = @person
    AND d.month = @month AND d.year = @year

C# code is as follows:

        SqlCommand commandSelect = new SqlCommand(query, conn);
        foreach (string[] p in pars)
        {
            commandSelect.Parameters.AddWithValue("@" + p[0], p[2]);
        }
        SqlDataReader res = commandSelect.ExecuteReader();

where there are 3 parameters passes and when I check SQLcommand in the debugger, they are passed correctly. @person is a string and the other two are integers.

Any help would be appreciated.

EDIT:
I probably should also add the stucture of pars array:

pars[0][0] = "person"
pars[0][2] = "'IDString here'"
pars[1][0] = "month"
pars[1][2] = "2"
pars[2][0] = "year"
pars[2][2] = "2012"

Answer 1

Well, looks like the problem was that addWithValue() casts strings to NVARCHAR, which I believe caused trouble in WHERE clause, because my field was of VARCHAR type. Explicit typecasting solved the problem.