ORA-02266錯誤的批量解決方案
ORA-02266: unique/primary keys in table referenced by enabled foreign keys 這篇部落格是很早之前總結的一篇文章，最近導數時使用TRUNCATE 清理主表資料又遇到了這個錯誤，發現還有其它解決方案：
a) 禁用與主表相關的外來鍵約束
b) TRUNCATE TABLE
c) 啟用那些外來鍵約束。
在實際操作中，發現使用上面的流程操作雖然正確，但是要寫很多指令碼，有些主表中的欄位可能是多個表的外來鍵約束。那麼我們必須寫多個指令碼，那麼我們必須使用指令碼批量生成。具體如下所示：。
-- 生成禁用約束的指令碼 , 解決 ORA-02266: unique/primary keys in table referenced by enabled foreign keys
SELECT DC.OWNER AS "PARENT_TABLE_OWNER",
DC.TABLE_NAME AS "PARENT_TABLE_NAME",
DC.CONSTRAINT_NAME AS "PRIMARY CONSTRAINT NAME",
DF.CONSTRAINT_NAME AS "REFERENCED CONSTRAINT NAME",
DF.OWNER AS "CHILD_TABLE_OWNER",
DF.TABLE_NAME AS "CHILD_TABLE_NAME" ,
'ALTER TABLE ' || DF.OWNER || '.' || DF.TABLE_NAME || ' DISABLE CONSTRAINT ' || DF.CONSTRAINT_NAME || ';'
FROM DBA_CONSTRAINTS DC,
(SELECT C.OWNER,
C.CONSTRAINT_NAME,
C.R_CONSTRAINT_NAME,
C.TABLE_NAME
FROM DBA_CONSTRAINTS C
WHERE CONSTRAINT_TYPE = 'R') DF
WHERE DC.CONSTRAINT_NAME = DF.R_CONSTRAINT_NAME
AND DC.OWNER =UPPER('&OWNER')
AND DC.TABLE_NAME=UPPER('&TABLE_NAME');
-- 生成啟用約束的指令碼 , 解決 ORA-02266: unique/primary keys in table referenced by enabled foreign keys
SELECT DC.OWNER AS "PARENT_TABLE_OWNER",
DC.TABLE_NAME AS "PARENT_TABLE_NAME",
DC.CONSTRAINT_NAME AS "PRIMARY CONSTRAINT NAME",
DF.CONSTRAINT_NAME AS "REFERENCED CONSTRAINT NAME",
DF.OWNER AS "CHILD_TABLE_OWNER",
DF.TABLE_NAME AS "CHILD_TABLE_NAME" ,
'ALTER TABLE ' || DF.OWNER || '.' || DF.TABLE_NAME || ' ENABLE CONSTRAINT ' || DF.CONSTRAINT_NAME || ';'
FROM DBA_CONSTRAINTS DC,
(SELECT C.OWNER,
C.CONSTRAINT_NAME,
C.R_CONSTRAINT_NAME,
C.TABLE_NAME
FROM DBA_CONSTRAINTS C
WHERE CONSTRAINT_TYPE = 'R') DF
WHERE DC.CONSTRAINT_NAME = DF.R_CONSTRAINT_NAME
AND DC.OWNER =UPPER('&OWNER')
AND DC.TABLE_NAME=UPPER('&TABLE_NAME');
原因分析：對於由FOREIGN KEY 約束引用的表，不能使用TRUNCATE TABLE ，因為TRUNCATE 不會觸發觸發器，不會去驗證任何約束。所以語法上是不允許的：有外來鍵約束的表只能用DELETE，不能用TRUNCATE。
You cannot truncate a table with an enabled foreign key that points to it. Truncate does not fire any triggers, does not validate any constraints. It does not care of the child table is empty or not -- in this case the child table might actually not be empty.