Already Exist

Bhuvana

14y2.7k.NET

DropDownList:
From the dropdownlist box we select the name if the name is already register in database means we got the message as already register how i do it.

5 Replies

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Satyapriya Nayak14y ago
Hi Bhuvana,

Try this...

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Dropdownlist_Already_Exist._Default" %>

    Untitled Page






                    onselectedindexchanged="DdlUserName_SelectedIndexChanged">



            ForeColor="Black">




using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;
namespace Dropdownlist_Already_Exist
{
    public partial class _Default : System.Web.UI.Page
    {
        string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        SqlCommand com;
        string str = null;

        protected void Page_Load(object sender, EventArgs e)
        {
            DdlUserName.AutoPostBack = true;
            SqlConnection con = new SqlConnection(connStr);

            if (!IsPostBack)
            {
                DdlUserName.Items.Add("Choose employee");
                con.Open();
                str = "select * from employee";
                com = new SqlCommand(str, con);
                SqlDataReader reader = com.ExecuteReader();
                while (reader.Read())
                {
                    DdlUserName.Items.Add(reader["ename"].ToString());
                }
                reader.Close();
                con.Close();
            }
        }
        public void namecheck()
        {
            SqlConnection con = new SqlConnection(connStr);
            con.Open();
            str = "select count(*)from employee where ename='" + DdlUserName.Text + "'";
            com = new SqlCommand(str, con);
            int count = Convert.ToInt32(com.ExecuteScalar());
            if (count > 0)
            {
                lblMessage.Text = "Already Exist";
            }
            else
            {
                lblMessage.Text = "Not Exist";
            }

        }

        protected void DdlUserName_SelectedIndexChanged(object sender, EventArgs e)
        {
            namecheck();
        }
    }
}

Thanks
If this post helps you mark it as answer
Keyur Narkhi14y ago
Hi

You can set your name as an unique key in the Database.then on the final save if you are trying to save same name which is already in the db then it will give you an sql exception then you can handle that and display the message to user.

hope this helps.

Thanks
V S N Raju Kanumuri14y ago
Hi

Try this

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection("connection string");
SqlDataAdapter da = new SqlDataAdapter("select name from employee where name='" +DropDownList1.SelectedItem + "' and date='" + date + "'", con);
DataTable dt = new DataTable();
da.Fill(dt);
if (dt.Rows.Count == 0)
{
//your code
}
else
{
// write message Values already exist

}
}
Bhuvana14y ago
logic means i can't understand pls explain it with c# code itself
Senthilkumar14y ago
Hi,

You need to do two things in the drop down list.

1) Set the property AutoPostBack=True in the drop down list
2) Write the index change event or double click the drop downlist

In the Indexchangedevent you need to get the value of selected,

ddl1.SelectedItem.Text
ddl1.SelectedItem.Value

then write the logic to check in the database, based on that you can show the error message.