Calling SQL Functions directly from C#

Question

I have a requirement to run a query against a database that will return either a zero or one (Checking for existance of specific criteria). The Tech specs I've been given for review state that I should be creating a stored procedure, that will return a single row, with a single column called "result" that will contain a bit value of 0 or 1. However, I'm not sure that a stored procedure would be the best approach, but am a little unsure so thought I'd ask for you opinions. The two options I can think of are:

1: Create a SQL scalar-valued function that performs the query and returns a bit. This could then be called directly from within the .Net client application using a "TEXT" SqlCommand object, and it would return a bool from the "ExecuteScalar()" method.

2: Create a stored procedure as described in the tech specs. This would then be called from the .Net Client app in the normal manner, and would return a DataTable with a single row and single column, that contains the bit value.

To me, option one seems the best. However, something in the back of my head is saying this isn't such a good idea.

Please could you give your opinions and help relieve my concerns? :)

Cheers, Ian

Answer 1

Execute the Stored Procedure using the ExecuteScalar() method. You can then cast the result of this to a boolean.

e.g

   SqlConnection con = new SqlConnection(connectionString);
    SqlCommand com = new SqlCommand("Execute dbo.usp_MyStoredProc", con);
    return (Boolean)com.ExecuteScalar();

Answer 2

This works for me and is based on this answer https://stackoverflow.com/a/3232556/1591831 using a SqlDataAdapter (note that you do not need to use one) and ExecuteScalar (can use ExecuteNonQuery as shown here):

bool res = false;
using (SqlConnection conn = new SqlConnection(GetConnectionString()))
{
    using (SqlCommand comm = new SqlCommand("dbo.MyFunction", conn))
    {
        comm.CommandType = CommandType.StoredProcedure;

        SqlParameter p1 = new SqlParameter("@MyParam", SqlDbType.Int);
        // You can call the return value parameter anything, .e.g. "@Result".
        SqlParameter p2 = new SqlParameter("@Result", SqlDbType.Bit);

        p1.Direction = ParameterDirection.Input;
        p2.Direction = ParameterDirection.ReturnValue;

        p1.Value = myParamVal;

        comm.Parameters.Add(p1);
        comm.Parameters.Add(p2);

        conn.Open();
        comm.ExecuteNonQuery();

        if (p2.Value != DBNull.Value)
            res = (bool)p2.Value;
    }
}
return res;