如何在相同条件下从 2 表中获取值

Question

我有 2 个表，t_silm 和 t_revenue，我想用相同的条件将两个表相加。这是我的表示例：https://ibb.co/JtCp80wt_silmbl - th - tw - total10 - 2018 - 4 - 10011 - 2018 - 4 - 20012 - 2018 - 4 - 300t_revenuebl - th - tw - jumlah10 - 2018 - 4 - 2511 - 2018 - 4 - 7012 - 2018 - 4 - 45我想得到结果：avg = total / jumlah;condition =  tw =4 and th = 2018;请有人可以帮助我吗？$query = "SELECT sum(t_slim.pemakaian_309) as to1, sum(t_revenue.jumlah) as to2, to1/to2 as taverage             from t_slim t1 INNER JOIN t_revenue t2 on t1.tahun=t2.tahun             and t1.triwulan=t2.triwulan WHERE t1.tahun=$tahun and t1.triwulan=$triwulan GROUP BY bulan";    $hasil = mysql_query($query);  $baris = 3;   while ($data = mysql_fetch_array($hasil))  {  $worksheet2->write_string(11, $baris, number_format($data['taverage'],2),$format2);  $baris++;    }