第一次寫觸發器，就有bug了

   前臺用ajax儲存使用者的修改和刪除，這時需求要加個觸發器，在修改和刪除時修改其他表的欄位，加完觸發器，點儲存，前臺彈出js錯誤，以為是js寫的有誤，結果查了半天js發現是ajax返回是出錯。

   後臺則為：2012-02-28 13:05:11,960 WARN [http-8080-Processor23] [RequestProcessor] Unhandled Exception thrown: class org.springframework.jdbc.BadSqlGrammarException。

    原來還是觸發器有問題，用PL/SQL寫的觸發器，沒有測試，最後不用程式單走觸發器，測試了一下觸發器，發現提示錯誤資訊為：ora-04091:表TB_JDF_XC.....發生了變化，觸發器/函式不能讀它。

    寫的觸發器如下：用PL/SQL developer寫的觸發器

    CREATE OR REPLACE TRIGGER TB_PER_POSITONLEVEL_TRI

Sql程式碼  

1. <span><span><span>AFTER INSERT OR UPDATE OF c_effectivedate,c_postionlevel,c_postioncluster OR DELETE ON TB_PER_POSITONLEVEL   
2. FOR EACH ROW  
3. BEGIN  
4.      IF inserting THEN  
5.         UPDATE
    tb_inf_employee t SET t.c_positionlevel = ( SELECT c_postionlevel FROM (SELECT a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY a.c_effectivedate DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ),  
6.                                      t.c_positionorder = ( SELECT
    c_postioncluster FROM (SELECT a.c_postioncluster FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY a.c_effectivedate DESC,a.c_operatetime DESC) WHERE ROWNUM =1 );  
7.      END IF;  
8.      IF deleting THEN  
9.         UPDATE tb_inf_employee t SET t.c_positionlevel = ( SELECT c_postionlevel FROM (SELECT a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid ORDER BY a.c_effectivedate DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ),  
10.                                      t.c_positionorder = ( SELECT c_postioncluster FROM (SELECT a.c_postioncluster FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid ORDER BY a.c_effectivedate DESC,a.c_operatetime DESC) WHERE ROWNUM =1 );  
11.      END IF;  
12.      IF UPDATing THEN  
13.         UPDATE tb_inf_employee t SET t.c_positionlevel = ( SELECT c_postionlevel FROM (SELECT a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid ORDER BY a.c_effectivedate DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ),  
14.                                      t.c_positionorder = ( SELECT c_postioncluster FROM (SELECT a.c_postioncluster FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid ORDER BY a.c_effectivedate DESC,a.c_operatetime DESC) WHERE ROWNUM =1 );  
15.      END IF;                                 
16. END TB_PER_POSITONLEVEL_TRI;</span></span></span>  

--手動 insert update delete測試

SELECT * FROM TB_PER_POSITONLEVEl r WHERE r.c_empoid = '853949' FOR UPDATE --853949

SELECT * FROM tb_inf_employee t WHERE t.c_employeeid = '853949'

   上網搜尋了一天觸發器，答案不給力，後來搜尋ORA-04091有了眉目，以後oracle的問題，直接搜尋問題編號就好了。

   結果如下：程式碼涉及到對關聯表的資料操作，比如查詢關聯表的總記錄數或者往關聯表中插入一條記錄，該型別程式碼只能在語句級觸發器中使用，如果在行級觸發器中使用，將會報ORA-04091錯誤。oracle的意思是要是涉及子查詢說明你資料庫設計上就有問題！

   那我又要用行級觸發器咋麼辦呢？

方法一：新建了與orginfo結構完全相同的臨時表tmp_orginfo，使得在orginfo上的觸發器讀寫tmp_orginfo,再用tmp_orginfo上的觸發器寫回orginfo,解決ora-04091問題。

方法二：開啟自治事務

   oracle行級觸發器無法讀取當前表的資料，為達到操作本表的效果建議開啟自治事務
create or replace trigger TRI_ACTION_LOG

after insert on action_log
for each row
declare
PRAGMA AUTONOMOUS_TRANSACTION;
co integer;
begin
    select count(1) into co from action_log;
    :new.log_state:=co;
    insert into action_log(log_state)
    values(:New.log_state);
    commit;
end; 把子查詢放到中間變數裡面，並用自治事務修改如下：

   CREATE OR REPLACE TRIGGER TB_PER_POSITONLEVEL_TRI

AFTER INSERT OR UPDATE OF c_effectivedate,c_postionlevel,c_postioncluster OR DELETE ON TB_PER_POSITONLEVEL

FOR EACH ROW

DECLARE

position_effdate DATE;

position_level varchar2(64);

position_order varchar2(64);

position_oid varchar2(128);

cou NUMBER(3);

PRAGMA AUTONOMOUS_TRANSACTION;

BEGIN

     --SELECT COUNT(*) INTO cou FROM (SELECT a.c_oid FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC);

     --INSERT INTO A_TEMP VALUES(cou);

     IF inserting THEN

        SELECT COUNT(*) INTO cou FROM (SELECT a.c_oid FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC);

       -- INSERT INTO A_TEMP VALUES('行級別觸發器after');

        --INSERT INTO A_TEMP VALUES(position_oid);

        --INSERT INTO A_TEMP VALUES( to_char(position_effdate,'fmdd month yyyy') );

        --INSERT INTO A_TEMP VALUES(position_level);

        --INSERT INTO A_TEMP VALUES(position_order);

        --INSERT INTO A_TEMP VALUES(cou);

        IF cou <> 0 THEN

           SELECT CASE WHEN :new.c_oid = c_oid THEN :NEW.c_postionlevel ELSE c_postionlevel END INTO position_level FROM (SELECT a.c_oid, a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC)  WHERE ROWNUM =1 ;

           SELECT CASE WHEN :new.c_oid = c_oid THEN :NEW.c_effectivedate ELSE c_effectivedate END INTO position_effdate FROM (SELECT a.c_oid,a.c_effectivedate FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

           SELECT CASE WHEN :new.c_oid = c_oid THEN :new.c_postioncluster ELSE c_postioncluster END INTO position_order FROM (SELECT a.c_oid,a.c_postioncluster FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

           SELECT c_oid INTO position_oid FROM (SELECT a.c_oid FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

           IF position_effdate <= :NEW.c_effectivedate THEN

              --INSERT INTO A_TEMP VALUES('插入的是最新的');

              UPDATE tb_inf_employee t SET t.c_positionlevel = :NEW.c_postionlevel,

                                      t.c_positionorder = :NEW.c_postioncluster WHERE t.c_employeeid = :NEW.C_EMPOID;

            END IF;

            ELSIF position_effdate > :NEW.c_effectivedate THEN

              --INSERT INTO A_TEMP VALUES('插入的不是最新的，沒有影響');

              UPDATE tb_inf_employee t SET t.c_positionlevel = position_level,

                                      t.c_positionorder = position_order WHERE t.c_employeeid = :NEW.C_EMPOID;

            END IF;

        END IF;

        IF cou = 0 THEN

           UPDATE tb_inf_employee t SET t.c_positionlevel = :NEW.c_postionlevel,

                                      t.c_positionorder = :NEW.c_postioncluster WHERE t.c_employeeid = :NEW.C_EMPOID;

        END IF;

     IF deleting THEN

        SELECT COUNT(*) INTO cou FROM (SELECT a.c_oid FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC);

       -- INSERT INTO A_TEMP VALUES('行級別觸發器after');

        --INSERT INTO A_TEMP VALUES(position_oid);

       -- INSERT INTO A_TEMP VALUES( to_char(position_effdate,'fmdd month yyyy') );

       -- INSERT INTO A_TEMP VALUES(position_level);

        --INSERT INTO A_TEMP VALUES(position_order);

      --  IF(:OLD.c_oid == )

        IF cou <> 1 THEN

        SELECT c_postionlevel INTO position_level FROM (SELECT a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid AND a.c_oid <> :old.c_oid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

        SELECT c_effectivedate INTO position_effdate FROM (SELECT a.c_effectivedate FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid AND a.c_oid <> :old.c_oid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

        SELECT c_postioncluster INTO position_order FROM (SELECT a.c_postioncluster FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid AND a.c_oid <> :old.c_oid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

        SELECT c_oid INTO position_oid FROM (SELECT a.c_oid FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :OLD.c_empoid AND a.c_oid <> :old.c_oid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

        UPDATE tb_inf_employee t SET t.c_positionlevel = position_level,

                                     t.c_positionorder = position_order WHERE t.c_employeeid = :OLD.C_EMPOID;

        END IF;

        IF cou = 1 THEN

        UPDATE tb_inf_employee t SET t.c_positionlevel = '',

                                     t.c_positionorder = '' WHERE t.c_employeeid = :OLD.C_EMPOID;

        END IF;

     END IF;

     IF UPDATing THEN

        SELECT CASE WHEN :new.c_oid = c_oid THEN :NEW.c_postionlevel ELSE c_postionlevel END INTO position_level FROM (SELECT a.c_oid, a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC)  WHERE ROWNUM =1 ;

        SELECT CASE WHEN :new.c_oid = c_oid THEN :NEW.c_effectivedate ELSE c_effectivedate END INTO position_effdate FROM (SELECT a.c_oid,a.c_effectivedate FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

        SELECT CASE WHEN :new.c_oid = c_oid THEN :new.c_postioncluster ELSE c_postioncluster END INTO position_order FROM (SELECT a.c_oid,a.c_postioncluster FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

        SELECT c_oid INTO position_oid FROM (SELECT a.c_oid FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC) WHERE ROWNUM =1 ;

        --INSERT INTO A_TEMP VALUES('行級別觸發器after');

        --INSERT INTO A_TEMP VALUES(position_oid);

       -- INSERT INTO A_TEMP VALUES( to_char(position_effdate,'fmdd month yyyy') );

       -- INSERT INTO A_TEMP VALUES(position_level);

       -- INSERT INTO A_TEMP VALUES(position_order);

        UPDATE tb_inf_employee t SET t.c_positionlevel = position_level,

                                     t.c_positionorder = position_order WHERE t.c_employeeid = :NEW.C_EMPOID;

     END IF;

    COMMIT;

END TB_PER_POSITONLEVEL_TRI;

--測試

SELECT * FROM TB_PER_POSITONLEVEl r WHERE r.c_empoid = '853949' FOR UPDATE --853949

INSERT INTO TB_PER_POSITONLEVEl(c_oid,c_empoid,c_effectivedate)  VALUES('22','853949',to_date('2012-02-10','yyyy-mm-dd'));

DELETE FROM TB_PER_POSITONLEVEl WHERE c_empoid = '853949' AND c_oid = '22'

SELECT t.c_positionlevel,t.c_positionorder FROM tb_inf_employee t WHERE t.c_employeeid = '853949'

UPDATE tb_inf_employee t SET t.c_positionlevel = '11',

                                     t.c_positionorder = '11' WHERE t.c_employeeid = '853949';

SELECT a.c_postioncluster FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = '853949' ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC

SELECT a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = '853949' ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC

SELECT * FROM A_TEMP

DELETE FROM a_temp WHERE 1 = 1  

    結果發現這裡的子查詢的結果不包括已經修改的記錄，就是說before和after在查詢關聯表的情況下是沒有區別的，不知道是怎麼個情況，就不包括正在crud的那條記錄，去掉自治事務，則報錯ora：04091，後來又加了一個額外的判斷看把查詢出來的結果和new、old比較，判斷是否修改的是要查的記錄。

SELECT CASE WHEN :new.c_oid = c_oid THEN :NEW.c_postionlevel ELSE c_postionlevel END INTO position_level FROM (SELECT a.c_oid, a.c_postionlevel FROM TB_PER_POSITONLEVEl a,tb_inf_employee b WHERE a.c_empoid = b.c_employeeid AND  a.c_empoid = :NEW.c_empoid ORDER BY nvl(a.C_EFFECTIVEDATE,TO_DATE('1900/01/01 00:00:00', 'YYYY/MM/DD HH24:MI:SS') ) DESC,a.c_operatetime DESC)  WHERE ROWNUM =1 ;

    暫時能用了，不過應該寫的很不規範。以後在研究吧。

    問題分析：就目前的線索來說，在觸發器中不讓用關聯表使用子查詢，mutating table（估計是正在修改的那條記錄沒有提交呢！！），要是非要這麼用，就用自治事務，這時要注意，無論before，after都是不包括正在crud的那條記錄，這說明其實觸發器的執行過程中after和before其實都沒有實際的更新資料庫，crud操作和觸發器body是在同一個事務中的，after是（crud、觸發器body commit的順序），before是（觸發器body、crud commit的順序）。都是最後一起提交事務，所謂before和after是說在同一個事務中的先後順序罷了。採用自治事務after應該能達到先crud、在子查詢中應該能查到剛才crud的那條記錄的，可是實際情況是沒有那條記錄，這說明oracle在實現觸發器的時候有內部的一套機制，需要深入研究才行，目前開發階段不涉及，以後有時間再研究吧。