title: If not exists then insert else show message "Already exists"
body: <pre><code>using System;
  using System.Collections.Generic;
  using System.ComponentModel;
  using System.Data;
  using System.Drawing;
  using System.Linq;
  using System.Text;
  using System.Windows.Forms;
  using System.Data.SqlClient;
  
  namespace Barcode
  {
      public partial class Form1 : Form
      {
          public Form1()
          {
              InitializeComponent();
          }
  
          private void button1_Click(object sender, EventArgs e)
          {
              string strconn = @"Data Source=ASHWINI-LAPY\SQLEXPRESS;Initial Catalog=complete;Integrated Security=True;Pooling=False";
              SqlDataReader reader = null;
  
              SqlConnection conn = null;
  
              conn = new SqlConnection(strconn);
              conn.Open();
  
              DateTime Dt_Time = DateTime.Now;
              string Barcode = textBox1.Text;
              SqlCommand cmd = new SqlCommand("select Barcode from table3 where @Barcode='" + textBox1.Text + "'", conn);
              cmd.Parameters.AddWithValue("@Barcode", textBox1.Text);
              reader = cmd.ExecuteReader();
              if (reader != null &amp;&amp; reader.HasRows)
              {
                  //email exists in db do something
  
                  MessageBox.Show("Barcode Already Exists!!");
  
              }
              else
              {
                  string strquery = string.Format("insert into table3 values('{0}','{1}')", Barcode, Dt_Time);
  
  
                  cmd = new SqlCommand(strquery, conn);
  
  
                  int count = (int)cmd.ExecuteNonQuery();
                  MessageBox.Show("Barcode:" + Barcode +
                                  "\nTime" + Dt_Time);
  
  
  
              }
  </code></pre>
  
  <p>I am new to C# coding so I tried to do it like what I mentioned below in code, so please somebody help me.</p>
  
  <p>I want to insert a barcode manually and when I press button the SQL Server database has to be checked whether that barcode exists. If not, it has to insert that barcode into the database, but if it already exists, it has to give a message that barcode already exists! </p>
  
  <p>Along with inserting barcode I am also inserting system date and time also in database.</p>