關於 oracle 外鍵引用 與 goldengate

一、準備知識
約束放置在表中，有以下五種約束:
 NOT NULL          非空約束C     指定的列不允許為空白值
 UNIQUE             唯一約束U     指定的列中沒有重複值，或該表中每一個值或者每一組值都將是唯一的
 PRIMARY KEY       主鍵約束P     唯一的標識出表的每一行,且不允許空值值,一個表只能有一個主鍵約束
 FOREIGN KEY       外鍵約束R     一個表中的列引用了其它表中的列，使得存在依賴關係，可以指向引用自身的列
 CHECK              條件約束C     指定該列是否滿足某個條件
約束命名規則
 如果不指定約束名Oracle server 自動按照SYS_Cn 的格式指定約束名，也可手動指定，
 推薦的約束命名是：約束類型_表名_列名。
 NN：NOT NULL          非空約束，比如nn_emp_sal
 UK：UNIQUE KEY         唯一約束
 PK：PRIMARY KEY       主鍵約束
 FK：FOREIGN KEY       外鍵約束
 CK：CHECK             條件約束
外鍵約束是用來維護從表和主表的參考完整性的，所以外鍵約束要涉及兩個表。
 FOREIGN KEY: 在表級指定子表中的列
 REFERENCES: 標示在父表中的列
 ON DELETE CASCADE: 當父表中的列被刪除時，子表中相對應的列也被刪除
 ON DELETE SET NULL: 子表中相應的列置空
 
二、外鍵建立測試
foreign_main為主表
foreign_sub為從表
object_id做為foreign_sub的外鍵，參考主表foreign_main的object_id值
 
SQL> create table foreign_main as select object_id from all_objects;
Table created.
SQL> select count(*) from foreign_main;
  COUNT(*)
----------
     49571
SQL> create table foreign_sub as select object_id,object_name from all_objects;
Table created.
 
建議使用主表的主鍵做外鍵，即使不是主表的主鍵也應該是唯一約束的欄位做為外鍵
 
SQL> alter table foreign_main add constraint pk_fsid primary key(object_id);
Table altered.
 
SQL> delete from foreign_sub where object_name = 'FOREIGN_MAIN';
1 row deleted.
 
SQL> commit;
Commit complete.
 
SQL>  alter table foreign_sub add constraint fr_fssid foreign key(object_id) references foreign_main(object_id);
Table altered.
 
從表插入一條主表object_id中不存在的記錄測試
SQL> insert into foreign_sub values(1,'ts');
insert into foreign_sub values(1,'ts')
*
ERROR at line 1:
ORA-02291: integrity constraint (TEST.FR_FSSID) violated - parent key not found
提示主表資料不存在，從表不能建立主表不存在的object_id以保證完整性
 
三、串聯刪除測試
 
SQL>  alter table foreign_sub drop constraint fk_fs_oid;
Table altered.
SQL>  alter table foreign_sub add constraint fk_fs_oid foreign key(object_id) references foreign_main(object_id) on delete cascade;
Table altered.
 
cascade下仍然不能單獨更新主表外鍵欄位
 
SQL> update foreign_main set object_id=52012 where object_id=52010;
update foreign_main set object_id=52012 where object_id=52010
*
ERROR at line 1:
ORA-02292: integrity constraint (TEST.FK_FS_OID) violated - child record found
 
cascade模式下可以通過主表刪除外鍵欄位資料關聯刪除從表資料
 
SQL> select * from foreign_sub where object_id=52010;
 OBJECT_ID OBJECT_NAME
---------- ------------------------------
     52010 IDX_BJNAME
 
SQL> delete from foreign_main where object_id=52010;
1 row deleted.
 
SQL> commit;
Commit complete.
 
SQL> select * from foreign_sub where object_id=52010;
no rows selected
 
外鍵相關常用操作及參考文檔
 
建立外鍵
alter table 表名 add constraint 外鍵名 foreign key(從表外鍵欄位) references foreign_main(主表外鍵欄位);
drop表外鍵
alter table 表名 drop constraint 外鍵名;
通過外鍵找表
select * from user_constraints where constraint_type='R' and constraint_name=upper('外鍵名');
通過表找外鍵
select * from user_constraints where constraint_type='R' and table_name=upper('表名');
尋找表的外鍵（包括名稱，參考資料表的表名和對應的鍵名，下面是分成多步查詢）：
select * from user_constraints c where c.constraint_type = 'R' and c.table_name = 要查詢的表
查詢參考資料表的鍵的列名：
select * from user_cons_columns cl where cl.constraint_name = 外鍵參考資料表的鍵名
 
外鍵約束臨時disabled
alter table 表名 disable constraint 外鍵名;
 
在SQL92標準中定義了幾種外鍵改變後，如何處理子表記錄的動作，其中包括：
 
限制Restrict：這種方式不允許對被參考的記錄的鍵值執行更新或刪除的操作；置為空白Set to null：當參考的資料被更新或者刪除，那麼所有參考它的外鍵值被置為空白；
置為預設值Set to default：當參考的資料被更新或者刪除，那麼所有參考它的外鍵值被置為一個預設值；
級聯Cascade：當參考的資料被更新，則參考它的值同樣被更新，當參考的資料被刪除，則參考它的子表記錄也被刪除；
不做操作No action：這種方式不允許更新或刪除被參考的資料。和限制方式的區別在於，這種方式的檢查發生在語句執行之後。Oracle預設才會的方式就是這種方式。
 
Col OWNER FOR A6
COL R_OWNER FOR A6
COL TABLE_NAME FOR A15
select OWNER, TABLE_NAME, CONSTRAINT_NAME, CONSTRAINT_TYPE, R_OWNER, R_CONSTRAINT_NAME, DELETE_RULE from user_constraints where table_name in ('FOREIGN_MAIN', 'FOREIGN_SUB');
 
Select CONSTRAINT_NAME from user_constraints e where e.table_name='IMS_COLUMN' and owner='WSJD_ELMS6';
Select b.table_name,b.column_name, A.CONSTRAINT_TYPE, C.TABLE_NAME from user_constraints a, user_cons_columns b, user_constraints C
WHERE a.constraint_name = b.constraint_name AND
A.R_CONSTRAINT_NAME = C.CONSTRAINT_NAME
AND a.r_constraint_name IN (Select CONSTRAINT_NAME from user_constraints e where e.table_name='FOREIGN_MAIN' and owner='SCOTT');
create table foreign_sub as select  object_id, object_name from user_objects;
 
create table foreign_main as select object_id from foreign_sub;
 
alter table foreign_main add constraint pk_foreign_main_object_id primary key(object_id);
 
alter table foreign_sub add constraint fr_foreign_sub_object_id foreign key(object_id) references foreign_main(object_id) on delete cascade;
 
alter table foreign_sub drop constraint fr_foreign_sub_object_id;
 
alter table foreign_sub disable constraint fr_foreign_sub_object_id;
 
如在goldengate 沒有禁用外鍵約束會出現以現錯誤
=============================================
2013-12-26 04:51:25  INFO    OGG-00996  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  REPLICAT REP_APP started.
2013-12-26 04:51:25  WARNING OGG-00869  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  OCI Error ORA-02292: integrity constraint (SCOTT.FR_FOREIGN_SUB_OBJECT_ID) violated - child record found (status = 2292). DELETE FROM "SCOTT"."FOREIGN_MAIN"  WHERE "OBJECT_ID" = :b0.
2013-12-26 04:51:25  WARNING OGG-01004  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Aborted grouped transaction on 'SCOTT.FOREIGN_MAIN', Database error 2292 (OCI Error ORA-02292: integrity constraint (SCOTT.FR_FOREIGN_SUB_OBJECT_ID) violated - child record found (status = 2292). DELETE FROM "SCOTT"."FOREIGN_MAIN"  WHERE "OBJECT_ID" = :b0).
2013-12-26 04:51:25  WARNING OGG-01003  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Repositioning to rba 17426 in seqno 29.
2013-12-26 04:51:25  WARNING OGG-01154  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  SQL error 2292 mapping SCOTT.FOREIGN_MAIN to SCOTT.FOREIGN_MAIN OCI Error ORA-02292: integrity constraint (SCOTT.FR_FOREIGN_SUB_OBJECT_ID) violated - child record found (status = 2292). DELETE FROM "SCOTT"."FOREIGN_MAIN"  WHERE "OBJECT_ID" = :b0.
2013-12-26 04:51:25  WARNING OGG-01003  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Repositioning to rba 17426 in seqno 29.
2013-12-26 04:51:25  ERROR   OGG-01296  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Error mapping from SCOTT.FOREIGN_MAIN to SCOTT.FOREIGN_MAIN.
2013-12-26 04:51:25  WARNING OGG-01525  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Failed to open trace output file, 'gglog-REP_APP.dmp', error 13 (Permission denied).
2013-12-26 04:51:25  ERROR   OGG-01668  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  PROCESS ABENDING.
 
2013-12-26 04:52:20  INFO    OGG-00996  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  REPLICAT REP_APP started.
2013-12-26 04:52:20  WARNING OGG-00869  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  No unique key is defined for table 'FOREIGN_SUB'. All viable columns will be used to represent the key, but may not guarantee uniqueness.  KEYCOLS may be used to define the key.
2013-12-26 04:52:20  WARNING OGG-01004  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Aborted grouped transaction on 'SCOTT.FOREIGN_SUB', Database error 1403 (OCI Error ORA-01403: no data found, SQL <DELETE FROM "SCOTT"."FOREIGN_SUB"  WHERE "OBJECT_ID" = :b0 AND "OBJECT_NAME" = :b1 AND ROWNUM = 1>).
2013-12-26 04:52:20  WARNING OGG-01003  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Repositioning to rba 17426 in seqno 29.
2013-12-26 04:52:20  WARNING OGG-01154  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  SQL error 1403 mapping SCOTT.FOREIGN_SUB to SCOTT.FOREIGN_SUB OCI Error ORA-01403: no data found, SQL <DELETE FROM "SCOTT"."FOREIGN_SUB"  WHERE "OBJECT_ID" = :b0 AND "OBJECT_NAME" = :b1 AND ROWNUM = 1>.
2013-12-26 04:52:20  WARNING OGG-01003  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Repositioning to rba 17426 in seqno 29.
2013-12-26 04:52:20  ERROR   OGG-01296  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Error mapping from SCOTT.FOREIGN_SUB to SCOTT.FOREIGN_SUB.
2013-12-26 04:52:20  WARNING OGG-01525  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  Failed to open trace output file, 'gglog-REP_APP.dmp', error 13 (Permission denied).
2013-12-26 04:52:20  ERROR   OGG-01668  Oracle GoldenGate Delivery for Oracle, rep_app.prm:  PROCESS ABENDING.