使用输出参数在ASP.NET中调用SQL存储过程

Question

I'm attempting to call my sql stored procedure which takes RaceDate as an input and returns Location as an OUTPUT. I'm not sure how to call my code in ASP.NET, this is what I have thus far.

DateTime RaceDate = Calendar1.SelectedDate;
    // string RaceDate = TxtBoxCalendar.Text;

    TxtBoxCalendar.ReadOnly = true;

    SqlConnection con = new SqlConnection();
    con.ConnectionString = ConfigurationManager.ConnectionStrings["RegistrationConnectionString"].ToString(); 

    con.Open();
    SqlCommand Command = new SqlCommand();

    Command.CommandType = System.Data.CommandType.StoredProcedure; 
    Command.CommandText = "CheckRaceCalendarDates";

    Command.Parameters.Add("@RaceDate", SqlDbType.DateTime, RaceDate);
    Command.Parameters.Add("@Location", SqlDbType.String).Direction = ParameterDirection.Output;

    Command.Parameters.Add("@Location",SqlDbType.String).Direction = ParameterDirection.Output;

    Command.ExecuteNonQuery();
    con.Close(); 

I think i may also run into a problem with datatypes. RaceDate is a date the user clicks through a calendar and has to be converted to a string however the SQL parameter RaceDate is of type date.

CREATE PROCEDURE [dbo].[CheckRaceCalendarDates]
@RaceDates DATE,
@Location NVARCHAR(50) OUTPUT
AS
IF EXISTS 
    (
SELECT 
    RaceCalendar.RaceDates,
    Locations.LocationName 
FROM 
    Locations
INNER JOIN RaceCalendar ON locations.LocationId = RaceCalendar.LocationId
WHERE 
    RaceCalendar.RaceDates = @RaceDates
    )

    BEGIN
SELECT 
    @Location = Locations.LocationName 
FROM 
    Locations
INNER JOIN RaceCalendar ON locations.LocationId = RaceCalendar.LocationId
WHERE 
    RaceCalendar.RaceDates = @RaceDates
    END

Answer 1

Your problem about using parameter name ; you have used @RaceDates on stored procedure but you try to use @RaceDate on code.. They should be same.

Also, you need to add second parameter to your code like this ;

Command.Parameters.Add("@Location",SqlDbType.String).Direction = ParameterDirection.Output;

And after cmd.ExeCuteNonQuery();

string location = Command.Parameters["@Location"].Value.ToString();