SQL：在更新

Question

我不能發現我的請求，問題誤差內加盟。這裏是我的要求和2臺：

UPDATE RESERVATION inner join client on reservation.numcl = client.numcl 
SET reservation.numcl2 = client.numcl2; 

錯誤：

=> [42000][971] ORA-00971: missing SET keyword 

1. 表客戶 Client table

2. 預訂客戶 reservation table

解決辦法：

UPDATE RESERVATION SET reservation.numcl2 = (select client.NUMCL2 
              from CLIENT 
              where client.NUMCL= RESERVATION.numcl); 

Answer 1

Oracle不支持在updatejoin（至少明確地）。你想要做什麼的等效是：

UPDATE RESERVATION r 
    SET numcl2 = (select client.NUMCL2 
        from CLIENT c 
        where c.NUMCL = r.numcl 
       ) 
    WHERE EXISTS (SELECT 1 FROM client c WHERE c.NUMCL = r.numcl); 

的exists是很重要的，如果你想處理在沒有比賽的案件。