SQL Server stored procedure return value, and using it in C#

Question

My application allows the user to add a new player to the database. Before adding a new player, I'd like for a stored procedure to check whether or not a player with the first name and last name exists. I want the stored procedure to return a bit value, 0 or 1 . My C# method will then return this value and the program can decide whether or not to proceed with the creation.

Note that I've cut some of the general validation out of the code below, ie if the fields are empty, or the balance TextBox is invalid etc..

I'm also aware that I may be using the wrong datatype when handling the returned value. ie int instead of bool .

When I run this, I get an error saying that my SP requires an input parameter @ReturnedValue .

Cheers

 Player newPlayer = new Player();
 newPlayer.PlayerID = Guid.NewGuid();
 newPlayer.FirstName = TextBoxFirstName.Text;
 newPlayer.LastName = TextBoxLastName.Text;
 newPlayer.Balance = Convert.ToDouble(TextBoxInitialCredit.Text);

var exists = newPlayer.CheckExists();

if (exists == 1)
{
     newPlayer.AddPlayer();
}

and here's the method:

 public int CheckExists()
 {
     SqlConnection myConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["Badminton"].ConnectionString);

     myConnection.Open();

     SqlCommand SqlCmd = new SqlCommand("CheckPlayerExists", myConnection);
     SqlCmd.CommandType = CommandType.StoredProcedure;

     SqlCmd.Parameters.Add("@FirstName", SqlDbType.NVarChar, 50).Value = FirstName;
     SqlCmd.Parameters.Add("@LastName", SqlDbType.NVarChar, 50).Value = LastName;
     SqlCmd.Parameters.Add("@ReturnValue", SqlDbType.Int, 2).Direction = ParameterDirection.Output;

     SqlDataAdapter myDataAdapter = new SqlDataAdapter(SqlCmd);
     DataSet myDataSet = new DataSet();
     myDataAdapter.Fill(myDataSet);

     int exists = Convert.ToInt32(SqlCmd.Parameters["@ReturnValue"].Value);

     myConnection.Close();

     return exists;
 }

and now my stored procedure:

CREATE PROCEDURE dbo.CheckPlayerExists
   @firstName nvarchar(50),
   @lastName nvarchar(50),
   @ReturnValue bit output
AS 
BEGIN
IF EXISTS (SELECT * FROM Players WHERE FirstName = @firstName AND LastName = @lastName)
        SET @ReturnValue = 1
ELSE
        SET @ReturnValue = 0

RETURN @ReturnValue
END

Answer 1

First, there's some inconsistency in your posted information. Is the parameter @ReturnValue or @ReturnedValue ? That alone could be the problem.

Second, either change your stored procedures declaration of the @ReturnedValue parameter to

@ReturnValue bit = 0 output

or change the C# code that adds the output parameter:

SqlParameter p = new SqlParameter();
p.ParameterName = "@ReturnedValue";
p.SqlDbType = SqlDbType.Int;
p.Value = 0;
p.Direction = ParameterDirection.InputOutput;
SqlCmd.Parameters.Add(p);

Answer 2

Problem : You are assigning the ParameterDirection Enum value as Output .

Solution : Change your ParameterDirection Enum value from Output to ReturnValue

ReturnValue: ParameterDirection.ReturnValue

The parameter represents a return value from an operation such as a stored procedure, built-in function, or user-defined function.

Replace This:

SqlCmd.Parameters.Add("@ReturnValue", SqlDbType.Int, 2).Direction
   = ParameterDirection.Output;

With This:

SqlCmd.Parameters.Add("@ReturnValue", SqlDbType.Int, 2).Direction
   = ParameterDirection.ReturnValue;

Answer 3

I think I see your issues. In the line:

SqlCmd.Parameters.Add("@ReturnValue", SqlDbType.Int, 2).Direction = ParameterDirection.Output;

change name and direction type to:

SqlCmd.Parameters.Add("@ReturnedValue", SqlDbType.Int, 2).Direction = ParameterDirection.ReturnValue;