username exist or not if exists choose differet name

Question

 

How to check username exists or not in sqlserver databse while registering the user if alredy exists show message alredy exists choose different name without using stored procedure .

 

asps.cs 

 

using System;

using System.Collections.Generic;

using System.Data.SqlClient;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace rummyRLodemo

{

public partial class registerex : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

SqlConnection con = new SqlConnection("Data Source=SHASHI\\SQLEXPRESS;Initial Catalog=Rummy;Integrated Security=True");

protected void btnRegister_Click(object sender, EventArgs e)

{

int userId = 0;

SqlCommand cmd = new SqlCommand();

using (SqlDataAdapter sda = new SqlDataAdapter())

{

cmd.Parameters.AddWithValue("@Username", UserName.Text.Trim());

cmd.Parameters.AddWithValue("@Password", password.Text.Trim());

cmd.Parameters.AddWithValue("@Email", email.Text.Trim());

cmd.Connection = con;

con.Open();

userId = Convert.ToInt32(cmd.ExecuteScalar());

con.Close();

}

string message = string.Empty;

switch (userId)

{

case -1:

message = "Username already exists.\\nPlease choose a different username.";

break;

case -2:

message = "Supplied email address has already been used.";

break;

default:

message = "Registration successful.\\nUser Id: " + userId.ToString();

break;

}

ClientScript.RegisterStartupScript(GetType(), "alert", "alert('" + message + "');", true);

}

}

}