how to check email is already there in database or not

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SQL-Server-2005

C#

SQL-Server

, +

hi
coding for forget password through gmail is working fine my question is how to check wheather email id is there in database or not if its not there execute please register first. how write coding for this
coding

using (SqlConnection con = new SqlConnection(_constr))
        {
            string query = "select Password,email from login where email='" + txtemail.Text + "'";
            SqlCommand cmd = new SqlCommand(query, con);
           
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);
             int  rowcount = ds.Tables[0].Rows.Count;
             if (rowcount > 0)
             {
                 email = ds.Tables[0].Rows[0]["email"].ToString();
                 password = ds.Tables[0].Rows[0]["password"].ToString();

                 MailMessage mail = new MailMessage();
                 mail.From = new MailAddress("gmailid");
                 mail.To.Add(email);
                 mail.Subject = "Reg. Password ";
                 mail.Body = " Your Password for the user" + " " + txtemail.Text.ToString() + " " + " is " + password;
                 mail.Priority = System.Net.Mail.MailPriority.High;
                 SmtpClient client = new SmtpClient();
                 client.Credentials = new System.Net.NetworkCredential("gmailid", "password");
                 client.Port = 587; // Gmail works on this port
                 client.Host = "smtp.gmail.com";
                 client.EnableSsl = true; //Gmail works on Server Secured Layer
                 //lbl6.Text = " The password has successfully sent to " + email;
                 client.Send(mail);      
            }
        }

my database coding is

01	CREATE PROCEDURE CheckUserName(  @User_Name VARCHAR(50) )
02	AS
03	BEGIN
04	 
05	  IF EXISTS (SELECT * FROM User_Table WHERE  [User_Name] = @User_Name ) 
06	 
07	  SELECT '1'; --user name already exist in database
08	 
09	  ELSE
10	 
11	  SELECT '0'; --user name does not exist in database
12	 
13	END