Question

I’m trying to pass a data table to a stored procedure. The table has four columns, OldDifficulty, OldIndex, NewDifficulty, and NewIndex. It is passed to a stored procedure which is supposed to update all the rows in a Puzzles table changing rows with the old index and difficulty to their new index and difficulty. The Puzzles table does not change, and I can’t figure out why. I’m not sure whether the problem is in the code or in the database query.

Here is the C# code that calls the stored procedure:

  var Form = context.Request.Form;
  DataTable table = new DataTable();
  table.Columns.Add("OldDifficulty");
  table.Columns.Add("OldIndex");
  table.Columns.Add("NewDifficulty");
  table.Columns.Add("NewIndex");
  foreach (var key in Form.Keys)
  {
    var Old = key.ToString().Split('_');
    var New = Form[key.ToString()].Split('_');
    if (Old == New || New.Length == 1 || Old.Length == 1) continue;
    table.Rows.Add(Old[0], int.Parse(Old[1]), New[0], int.Parse(New[1]));
  }
  using (var con = new SqlConnection(SqlHelper.ConnectionString))
  {
    con.Open();
    using (var com = new SqlCommand("RearrangePuzzles", con))
    {
      com.CommandType = CommandType.StoredProcedure;
      com.Parameters.Add(new SqlParameter("ChangedPuzzles", table) 
        { SqlDbType = SqlDbType.Structured });
      com.ExecuteNonQuery();
    }
    con.Close();
  }

and here is the stored procedure:

ALTER PROCEDURE [dbo].[RearrangePuzzles]
    @ChangedPuzzles ChangedPuzzlesTable READONLY
AS
UPDATE p 
SET 
    NthPuzzle = cp.NewIndex, 
    Difficulty = cp.NewDifficulty 
FROM 
    Puzzles p JOIN 
    @ChangedPuzzles cp ON cp.OldIndex = p.NthPuzzle AND cp.OldDifficulty = p.Difficulty

Do you have any idea why the table isn’t updating? Is there something wrong with my SQL?

Answer 1

Everything looks ok, except:

com.Parameters.Add(new SqlParameter("ChangedPuzzles", table) 
    { SqlDbType = SqlDbType.Structured });

I would change to:

com.Parameters.Add(new SqlParameter("@ChangedPuzzles", table) 
    { SqlDbType = SqlDbType.Structured });

@ sign – prefix in parameter name.

Use SQL Server Profiler to see whether this query actually is executed.