使用規則在Insert上更新sql值;有老

Question

問題，當我有一個表，就像

AccNum  Location 
76   North 
87   West 
92   South 

而且說我要再次插入76，但我只能把它在那裏曾經讓上插入（76，東）我想我的表看起來像

AccNum Location 
76  East 
87  West 
92  South 

這是我的代碼

CREATE RULE ChangeValue AS ON INSERT TO ItemLocations 
    WHERE OLD.AccNum = NEW.AccNum 
     DO INSTEAD 
       UPDATE ItemLocations 
       SET 
         Loc = NEW.Loc 
       WHERE 
         AccNum = NEW.AccNum 
; 

但我目前得到

There is an entry for table "old", but it cannot be referenced from this part of the query. 

感謝信

Answer 1

在Postgres裏95 +，你可以使用on conflict：

insert into t(AccNum, Location) 
    select 76, 'East' 
    on conflict do update set Location = 'East'; 

或者：

insert into t(AccNum, Location) 
    select 76, 'East' 
    on conflict do update set Location = EXCLUDED.Location;