How to properly remove the return value from a call to a stored procedure

First of all, I would like to thank anyone who reads this and responds. Your help is greatly appreciated!

I am developing an ASP.NET web application in which I need to read and write to a database. For this, I was trying to call from my C # code several stored procedures that I wrote. In particular, these are:

public static bool userExistsInDB(string username)
{
    int userExistsInDB = -1;
    using (SqlConnection con = new SqlConnection(DBConfig.DbConnectString))
    {
        using (SqlCommand cmd = new SqlCommand("tb_user_exists", con))
        {
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.Add("@username", SqlDbType.VarChar).Value = username;
            con.Open();
            userExistsInDB = cmd.ExecuteNonQuery();
        }
    }
    return userExistsInDB == 1;
}

      

        
        
        
      

    

The stored procedure I called was created using this SQL script:

CREATE PROCEDURE tb_is_logged_in
    @username VARCHAR(20)
AS
IF(EXISTS(SELECT * FROM logged_in_users WHERE "username" = @username))
BEGIN
    RETURN 1; 
END
ELSE
BEGIN
    RETURN 0; 
END

      

        
        
        
      

    

I tested it myself in SQL Server Management Studio and it seems to work. However, after navigating to my C # code, I found an issue with the line

userExistsInDB = cmd.ExecuteNonQuery();

      

        
        
        
      

    

The stored procedure should return 1 or 0 if the specified user exists in the database or not, respectively, and, as you can see, is userExistsInDB

initialized with -1

. However, after execution, the line userExistsInDB = cmd.ExecuteNonQuery();

userExistsInDB

never changes; it always retains its value -1

. So it seems that I am returning the value incorrectly. What am I doing wrong?

EDIT:

Thanks to Leonel, I found a solution to the problem. First, I realized that the stored procedure I inserted above was the wrong procedure. This is not the one I actually call in my C # code, and when I tried to fix Leonel it didn't work because I accidentally edited the procedure I inserted above instead of the one I'm actually calling. Here is the actual stored procedure I was calling:

CREATE PROCEDURE tb_user_exists
    @username VARCHAR(20)
AS
IF(EXISTS (SELECT * FROM users WHERE username = @username))
BEGIN
    RETURN 1;  
END
ELSE
BEGIN
    RETURN 0; 
END

      

        
        
        
      

    

My solution is this: change this line

userExistsInDB = cmd.ExecuteNonQuery();

      

        
        
        
      

    

to

userExistsInDB = (int)cmd.ExecuteScalar();

      

        
        
        
      

    

and change the stored procedure to:

CREATE PROCEDURE tb_user_exists
    @username VARCHAR(20)
AS
IF(EXISTS (SELECT * FROM users WHERE username = @username))
BEGIN
    SELECT 1;  
END
ELSE
BEGIN
    SELECT 0; 
END