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 r

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;

Answer 3

solving it with a stored procedure is better in the long run because it´s more flexible and adaptable

Answer 4

I suppose it depends on the logic the corresponding db function (sp/udf) has to execute.

If for e.g. we are interested in the number of times the particular db function has executed we'd definitely need to do some data manipulation and updates on various tables. Hence we'd have to go for stored procs here. If its a simple retrieval a udf will do.

Answer 5

The calling scalar-valued function is absolutely correct solution.

Answer 6

i use this sql scalar function

CREATE FUNCTION DAYSADDNOWK(@addDate AS DATE, @numDays AS INT)
RETURNS DATETIME
AS
BEGIN
    SET @addDate = DATEADD(d, @numDays, @addDate)
    IF DATENAME(DW, @addDate) = 'sunday'   SET @addDate = DATEADD(d, 1, @addDate)
    IF DATENAME(DW, @addDate) = 'saturday' SET @addDate = DATEADD(d, 2, @addDate)

    RETURN CAST(@addDate AS DATETIME)
END
GO

then this is my c# code

using (SqlCommand cmd3 = new SqlCommand("SELECT dbo.DAYSADDNOWK", ClassV.con))
                    ClassV.con.Open();
                    SqlCommand brecord = ClassV.con.CreateCommand();
                    brecord.CommandText = "INSERT INTO TblBorrowRecords VALUES ('" + DGStudents.CurrentRow.Cells[1].Value.ToString() + "','" + DGStudents.CurrentRow.Cells[2].Value.ToString() + "','" + DGStudents.CurrentRow.Cells[4].Value.ToString() + "','" + DGStudents.CurrentRow.Cells[3].Value.ToString() + "','" + DG.CurrentRow.Cells[4].Value.ToString() + "','" + DG.CurrentRow.Cells[5].Value.ToString() + "','" + DG.CurrentRow.Cells[6].Value.ToString() + "','" +System.DateTime.Now.Date.ToShortDateString() + "' , dbo.DAYSADDNOWK(GETDATE(),5) ,null , '" + ClassV.lname.ToString() + ", " + ClassV.fname.ToString() + " " + ClassV.mname.ToString() + "', null, 'Good',null)";
                    var DAYSADDNOWK = brecord.ExecuteScalar();

my C# code skips the function