CASE語句無所作爲

我有一個case語句的觸發器。在ELSE塊代碼的最後一部分，我希望觸發器不做任何事情，並且如果值在前面的CASE語句中不匹配，則退出。我如何做到這一點：CASE語句無所作爲

create or replace TRIGGER "CONVEYANCE_REQUEST_T3" 
BEFORE 
insert or update on "CONVEYANCE_REQUEST" 
for each row 
begin 

CASE 
when :NEW.REGULAR_TRAVEL_MODE = '2 WHEELER' THEN 
BEGIN 
    CASE 
     when :NEW.WAY_TYPE = 'ONE WAY' THEN 
       SELECT RATE_PER_KM * (SELECT DISTANCE_ONEWAY FROM  DISTANCE_MASTER WHERE PROJECT_CODE = :NEW.PROJECT_CODE) * 1 INTO  :NEW.REGULAR_AMOUNT FROM CONVEYANCE_RATE WHERE TRAVEL_MODE = :NEW.REGULAR_TRAVEL_MODE; 
     WHEN :NEW.WAY_TYPE ='TWO WAY' THEN 
       SELECT RATE_PER_KM * (SELECT DISTANCE_ONEWAY FROM DISTANCE_MASTER WHERE PROJECT_CODE = :NEW.PROJECT_CODE) * 2 INTO :NEW.REGULAR_AMOUNT FROM CONVEYANCE_RATE WHERE TRAVEL_MODE = :NEW.REGULAR_TRAVEL_MODE; 
    END CASE; 
END; 
when :NEW.REGULAR_TRAVEL_MODE = '4 WHEELER' THEN 
BEGIN 
    CASE 
     when :NEW.WAY_TYPE = 'ONE WAY' THEN 
       SELECT RATE_PER_KM * (SELECT DISTANCE_ONEWAY FROM DISTANCE_MASTER WHERE PROJECT_CODE = :NEW.PROJECT_CODE) * 1 INTO :NEW.REGULAR_AMOUNT FROM CONVEYANCE_RATE WHERE TRAVEL_MODE = :NEW.REGULAR_TRAVEL_MODE; 
     WHEN :NEW.WAY_TYPE ='TWO WAY' THEN 
       SELECT RATE_PER_KM * (SELECT DISTANCE_ONEWAY FROM DISTANCE_MASTER WHERE PROJECT_CODE = :NEW.PROJECT_CODE) * 2 INTO :NEW.REGULAR_AMOUNT FROM CONVEYANCE_RATE WHERE TRAVEL_MODE = :NEW.REGULAR_TRAVEL_MODE; 
    END CASE; 
END; 
ELSE 
    ****statement to just exit & not do anything***** 

END CASE; 
END;

來源

2016-06-14 Teju

如果你不想它做任何事情，那麼不要把其他東西放在那裏？ – Chris

我累了..但是當我想插入我使用APEX應用程序記錄時，它給出了以下錯誤：發生了1個錯誤 ORA-06592：執行CASE語句時未找到CASE ORA-06512：在「BABBLER_GROUP.CONVEYANCE_REQUEST_T3」，第3行ORA-04088：執行觸發器'BABBLER_GROUP.CONVEYANCE_REQUEST_T3'時出錯' – Teju

也許'else null;'？ –

這是一個非常複雜的情況下發言，基本上是重複每次相同的排序select語句。

由於每個語句之間的唯一差別是乘數是1還是2，你可以只改寫整個事情在一個case語句包含SQL語句的情況下，表情像這樣：

create or replace trigger "CONVEYANCE_REQUEST_T3" 
before 
insert or update on "CONVEYANCE_REQUEST" 
for each row 
begin 
    case when rate_per_km in ('2 WHEELER', '4 WHEELER') 
      and new.way_type in ('ONE WAY', 'TWO WAY') then 
      select rate_per_km 
        * (select distance_oneway from distance_master where project_code = :new.project_code) 
        * case when :new.way_type = 'ONE WAY' 
           then 1 
          when :new.way_type = 'TWO WAY' 
           then 2 
          else null 
        end regular_amount 
      into :new.regular_amount 
      from conveyance_rate where travel_mode = :new.regular_travel_mode; 
     else null; 
    end case; 
end; 
/

你甚至可以逃脫，因爲沒有外殼語句（儘管你必須將rate_per_km in ('2 WHEELER', '4 WHEELER')條件推入case表達式，但是每次對每行都必須運行查詢，並且如果大多數情況下可能會降低性能行被插入不是2或4輪車

來源

2016-06-14 13:48:30 Boneist

CASE語句無所作爲

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