string query = "UPDATE tblStudents INNER JOIN tblMarks ON tblStudents.StuID=tblMarks.StuID SET tblStudents.FirstName='" + txtFirstName.Text + "', tblStudents.LastName='" + txtLastName.Text + "', tblStudents.DOB='" + DateTime.ParseExact(dtpPickDate.Text, @"dd/MMM/yy", System.Globalization.CultureInfo.InvariantCulture) + "', tblStudents.UserName='" + txtUserName.Text + "', tblStudents.Password='" + txtPassword.Text + "', tblMarks.Mark1=" + int.Parse(txtMark1.Text) + ", tblMarks.Mark2=" + int.Parse(txtMark2.Text) + ", tblMarks.Mark3 = " + int.Parse(txtMark3.Text) + ", tblMarks.Mark4=" + int.Parse(txtMark4.Text) + ", tblMarks.Mark5=" + int.Parse(txtMark5.Text) + " WHERE tblStudents.StuID=" + int.Parse(txtStuID.Text);

//Button for saving new records
private void btnSaveNew_Click(object sender, EventArgs e)
{
    try
    {
        connection.Open();

        OleDbCommand command = new OleDbCommand();
        command.Connection = connection;

        string query = "insert tblStudents.*, tblMarks.* into tblStudents (FirstName,LastName,DOB,UserName,Password) values('" + txtFirstName.Text + "','" + txtLastName.Text + "','" + dtpPickDate.Text +"','" + txtUserName.Text + "','"+ txtPassword.Text+ "')";

        command.CommandText = query;
        command.ExecuteNonQuery(); //execute the query

        string query2 = "insert into tblMarks (Mark1,Mark2,Mark3,Mark4,Mark5) values('" +int.Parse(txtMark1.Text)  + "','" + int.Parse(txtMark2.Text) + "','" + int.Parse(txtMark3.Text) + "','" + int.Parse(txtMark4.Text) + "','" + int.Parse(txtMark5.Text) + "')";

        command.CommandText = query2;
        command.ExecuteNonQuery();

        MessageBox.Show("Data Saved");
        connection.Close();    // close database connection
    }
    catch (Exception ex)
    {
        MessageBox.Show("Error In Saving Edits Please Ensure that Data is Inputted Correctly  n n " + ex, "Important Note", MessageBoxButtons.OK, MessageBoxIcon.Error);
        connection.Close();
    }
}