The dbType NVarChar is invalid for this constructor

Question

    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void MyMethod()
    {
        string connectionString = "context connection=true";
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();
            SqlMetaData[] metaData = {
                                         new SqlMetaData("Column1", System.Data.SqlDbType.NVarChar)
                                         ,new SqlMetaData("Column1", System.Data.SqlDbType.NVarChar)
                                     };
            SqlDataRecord record = new SqlDataRecord(metaData);
            record.SetString(0,"hello world");
            SqlContext.Pipe.SendResultsRow(record);
        }
    }

When I run the method in SQL

EXEC MyMethod

Error

Msg 6522, Level 16, State 1, Procedure MyMethod, Line 0 A .NET Framework error occurred during execution of user-defined routine or aggregate "MyMethod": System.ArgumentException: The dbType NVarChar is invalid for this constructor. System.ArgumentException: at Microsoft.SqlServer.Server.SqlMetaData.Construct(String name, SqlDbType dbType, Boolean useServerDefault, Boolean isUniqueKey, SortOrder columnSortOrder, Int32 sortOrdinal) at Microsoft.SqlServer.Server.SqlMetaData..ctor(String name, SqlDbType dbType) at WcfClrApps.MyNamespace.MyMethod()

How can a return a record that I create myself? I do not want to run any SQL. Project build is set for .NET 3.5. MSDN indicates 4.0 is not supported in SQL 2008 R2.

Answer 1

The problem is two fold. 1. Max length is required. 2. SendResultsStart()/SendResultsEnd() are required.

    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void MyMethod()
    {
        string connectionString = "context connection=true";
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();
            SqlMetaData[] metaData = {
                                         new SqlMetaData("Column1", System.Data.SqlDbType.NVarChar, 100)//Max length has to be specified
                                         ,new SqlMetaData("Column1", System.Data.SqlDbType.NVarChar, 100)//same story
                                     };
            SqlDataRecord record = new SqlDataRecord(metaData);
            SqlContext.Pipe.SendResultsStart(record);//SendResultsStart must be called

            //create a row and send it down the pipe
            record.SetString(0,"hello world");
            SqlContext.Pipe.SendResultsRow(record);

            SqlContext.Pipe.SendResultsEnd();//End it out

        }
    }

Iterative example