Calling stored procedure with return value

问题:

I am trying to call a stored procedure from my C# windows application. The stored procedure is running on a local instance of SQL Server 2008. I am able to call the stored procedure but I am not able to retrieve the value back from the stored procedure. This stored procedure is supposed to return the next number in the sequence. I have done research online and all the sites I\'ve seen have pointed to this solution working.

Stored procedure code:

ALTER procedure [dbo].[usp_GetNewSeqVal]
      @SeqName nvarchar(255)
as
begin
      declare @NewSeqVal int
      set NOCOUNT ON
      update AllSequences
      set @NewSeqVal = CurrVal = CurrVal+Incr
      where SeqName = @SeqName

      if @@rowcount = 0 begin
print \'Sequence does not exist\'
            return
      end

      return @NewSeqVal
end

Code calling the stored procedure:

SqlConnection conn = new SqlConnection(getConnectionString());
conn.Open();

SqlCommand cmd = new SqlCommand(parameterStatement.getQuery(), conn);
cmd.CommandType = CommandType.StoredProcedure;

SqlParameter param = new SqlParameter();

param = cmd.Parameters.Add(\"@SeqName\", SqlDbType.NVarChar);
param.Direction = ParameterDirection.Input;
param.Value = \"SeqName\";

SqlDataReader reader = cmd.ExecuteReader();

I have also tried using a DataSet to retrieve the return value with the same result. What am I missing to get the return value from my stored procedure? If more information is needed, please let me know.

回答1:

You need to add return parameter to the command:

using (SqlConnection conn = new SqlConnection(getConnectionString()))
using (SqlCommand cmd = conn.CreateCommand())
{
    cmd.CommandText = parameterStatement.getQuery();
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.AddWithValue(\"SeqName\", \"SeqNameValue\");

    var returnParameter = cmd.Parameters.Add(\"@ReturnVal\", SqlDbType.Int);
    returnParameter.Direction = ParameterDirection.ReturnValue;

    conn.Open();
    cmd.ExecuteNonQuery();
    var result = returnParameter.Value;
}

回答2:

ExecuteScalar() will work, but an output parameter would be a superior solution.

回答3:

I know this is old, but i stumbled on it with Google.

If you have a return value in your stored procedure say \"Return 1\" - not using output parameters.

You can do the following - \"@RETURN_VALUE\" is silently added to every command object. NO NEED TO EXPLICITLY ADD

    cmd.ExecuteNonQuery();
    rtn = (int)cmd.Parameters[\"@RETURN_VALUE\"].Value;

回答4:

The version of EnterpriseLibrary on my machine had other parameters. This was working:

        SqlParameter retval = new SqlParameter(\"@ReturnValue\", System.Data.SqlDbType.Int);
        retval.Direction = System.Data.ParameterDirection.ReturnValue;
        cmd.Parameters.Add(retval);
        db.ExecuteNonQuery(cmd);
        object o = cmd.Parameters[\"@ReturnValue\"].Value;

回答5:

You can try using an output parameter. http://msdn.microsoft.com/en-us/library/ms378108.aspx

回答6:

I had a similar problem with the SP call returning an error that an expected parameter was not included. My code was as follows.
Stored Procedure:

@Result int OUTPUT

And C#:

            SqlParameter result = cmd.Parameters.Add(new SqlParameter(\"@Result\", DbType.Int32));
            result.Direction = ParameterDirection.ReturnValue;

In troubleshooting, I realized that the stored procedure was ACTUALLY looking for a direction of \"InputOutput\" so the following change fixed the problem.

            r

Result.Direction = ParameterDirection.InputOutput;

回答7:

Or if you\'re using EnterpriseLibrary rather than standard ADO.NET...

Database db = DatabaseFactory.CreateDatabase();
using (DbCommand cmd = db.GetStoredProcCommand(\"usp_GetNewSeqVal\"))
{
    db.AddInParameter(cmd, \"SeqName\", DbType.String, \"SeqNameValue\");
    db.AddParameter(cmd, \"RetVal\", DbType.Int32, ParameterDirection.ReturnValue, null, DataRowVersion.Default, null);

    db.ExecuteNonQuery(cmd);

    var result = (int)cmd.Parameters[\"RetVal\"].Value;
}

回答8:

I see the other one is closed. So basically here\'s the rough of my code. I think you are missing the string cmd comment. For example if my store procedure is call:DBO.Test. I would need to write cmd=\"DBO.test\". Then do command type equal to store procedure, and blah blah blah

Connection.open();
String cmd=\"DBO.test\"; //the command
Sqlcommand mycommand;