Remove (skip) duplicate record while importing excel file to database using C# in ASP.Net

Hi Kibock,

Refer the below sample code.

C#

protected void insertdata_Click(object sender, EventArgs e)
{
    OleDbConnection oconn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + Server.MapPath("Files/Export_To_konferanse_UserGroupVest.xlsx") + ";Extended Properties='Excel 8.0;HDR={1}'");
    try
    {
        OleDbCommand ocmd = new OleDbCommand("select * from [UserGroupVest$]", oconn);
        oconn.Open();
        OleDbDataReader odr = ocmd.ExecuteReader();
        string DeltakerName = "";
        string DeltakerEpost = "";
        string DeltakerTelefon = "";
        while (odr.Read())
        {
            DeltakerName = valid(odr, 0);
            DeltakerEpost = valid(odr, 1);
            DeltakerTelefon = valid(odr, 2);
            // Checking email exist or not.
            // If not exist then insert record.
            if (!IsEmailExist(DeltakerName, DeltakerEpost))
            {
                insertdataintosql(DeltakerName, DeltakerEpost, DeltakerTelefon);
            }
        }
        oconn.Close();
    }
    catch (DataException ee)
    {
        lblmsg.Text = ee.Message;
        lblmsg.ForeColor = System.Drawing.Color.Red;
    }
    finally
    {
        lblmsg.Text = "Data Inserted Sucessfully";
        lblmsg.ForeColor = System.Drawing.Color.Green;
    }
}

private bool IsEmailExist(string DeltakerName, string DeltakerEpost)
{
    bool exist = false;
    string conStr = ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
    SqlConnection conn = new SqlConnection(conStr);
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = conn;
    // Change the query as per your condition.
    string query1 = "SELECT DeltakerEpost FROM testAkonferanse_UserGroup WHERE DeltakerName = @DeltakerName AND DeltakerEpost = @DeltakerEpost";
    cmd.CommandText = query1;
    cmd.Parameters.Add("@DeltakerName", SqlDbType.NVarChar, 100).Value = DeltakerName;
    cmd.Parameters.Add("@DeltakerEpost", SqlDbType.NVarChar, 100).Value = DeltakerEpost;
    cmd.CommandType = CommandType.Text;
    conn.Open();
    object i = cmd.ExecuteScalar();
    if (i != null)
    {
        exist = true;
    }
    conn.Close();

    return exist;
}

protected string valid(OleDbDataReader myreader, int stval) //if any columns are found null then they are replaced by zero
{
    object val = myreader[stval];
    if (val != DBNull.Value)
        return val.ToString();
    else
        return Convert.ToString(0);
}

public void insertdataintosql(string DeltakerName, string DeltakerEpost, string DeltakerTelefon)
{
    string conStr = ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
    SqlConnection conn = new SqlConnection(conStr);
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = conn;
    string query1 = "INSERT INTO testAkonferanse_UserGroup (DeltakerName, DeltakerEpost, DeltakerTelefon) VALUES (@DeltakerName, @DeltakerEpost, @DeltakerTelefon);SELECT SCOPE_IDENTITY()";
    cmd.CommandText = query1;
    cmd.Parameters.Add("@DeltakerName", SqlDbType.NVarChar, 100).Value = DeltakerName;
    cmd.Parameters.Add("@DeltakerEpost", SqlDbType.NVarChar, 100).Value = DeltakerEpost;
    cmd.Parameters.Add("@DeltakerTelefon", SqlDbType.NVarChar, 100).Value = DeltakerTelefon;
    cmd.CommandType = CommandType.Text;
    conn.Open();
    cmd.ExecuteNonQuery();
    conn.Close();
    GridView1.DataBind();
}