i need quick answer for the question

OleDbConnection con = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Path.GetDirectoryName(Application.ExecutablePath) + "\\NBS.mdb;");
        OleDbCommand cmd;


string strSQL1 = ("insert into DailyTrans_Master (ReceiptNo,ReceiptDate,Cust_ID,Amt_paid,ForMonth,ForYear)");
                        strSQL1 += ("values ('" + txtReceiptNo.Text + "',Date()," + txtCustomerID.Text + "," + txtAmt.Text + ",'" + cmbMonth.Text + "','" + cmbYear.Text + "')");
                        con.Open();
                        cmd = new OleDbCommand(strSQL1, con);
                        cmd.ExecuteNonQuery();
                        con.Close();

string strSQL = "update Receipt_Master_" + cmbYear.Text + " set [Jan]= " + txtAmt.Text + " where [Cust_ID]= " + txtCustomerID.Text + "";
                        con.Open();
                        cmd = new OleDbCommand(strSQL, con);
                        cmd.ExecuteNonQuery();
                        con.Close();

string SQL = "delete from area_master where area_Name = '" + txtAreaName.Text + "' and area_Code = '" + txtAreaCode.Text + "'";
                con.Open();
                cmd = new OleDbCommand(SQL, con);
                cmd.ExecuteNonQuery();
                con.Close();