How to stop duplicate value?

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Dear All,

How could be remove the duplicate name when I click on save button and tell me it’s already exists

i am using above code for save name ,address etc. from the database.

C#

private void btnSave_Click(object sender, EventArgs e)
        {
            try
            {
                string connstr = @"Server=.\SQLEXPRESS ;Initial Catalog=RPSJDB;Integrated Security=True; Max Pool Size=100";
                string query = "insert into CustomerTable values('" + txtCustomerName.Text + "','" + txtAddress.Text + "','" + txtMobileNo.Text + "','" + lblGoldBalance.Text + "','" + lblSilverBalance.Text + "','" + lblCashBalance.Text + "')";
                SqlConnection conn = new SqlConnection(connstr);

                if (txtCustomerName.Text != "" & txtAddress.Text != "")
                {
                    conn.Open();
                    SqlCommand cmd = new SqlCommand(query, conn);
                    cmd.ExecuteNonQuery();

                    txtCustomerName.Clear();
                    txtAddress.Clear();
                    txtMobileNo.Clear();

                    MessageBox.Show("Values Save in DataBase");
                    conn.Close();
                }
                else
                {
                    MessageBox.Show("Only Mobile Field Can be Empty");
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("At Least 0 value can be save in the Gold Silver Cash Area",ex.Message);
                
            }

Posted 2-Sep-13 18:54pm

Manish Arya

Updated 2-Sep-13 18:57pm

Sushil Mate

v2

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Priyanka Bhagwat · Accepted Answer · 2013-09-02T19:02:00

Hi,
You can create a function which checks for the value from data base
here is the sample code.
1:You will write a function

C#

private Boolean usernameexists()
      {

              OleDbCommand com = new OleDbCommand("select Username from User_master where        Username ='" + txt_username.Text + "'", con);
              OleDbDataReader oledbrd1;
              oledbrd1 = com.ExecuteReader();
              if (oledbrd1.HasRows)
              {
                  oledbrd1.Read();
                      unameerrmsg.Visible = true;
                      unameerrmsg.Text = "username already exist";
                      oledbrd1.Close();
                      return true;

              }
              else
              {
                  unameerrmsg.Visible = false;
                  return false;
              }
          }

2: On your save button if username exist return

C#

if (usernameexists() == true)
           {
               return;
           }

You can also call this function on textbox textchanged()

hope this helps
Happy coding :)