Oracle maintain data integrity

1、data integrity:app code ,db trigger, integrity constraint 优先级增高
2、constraints type: not null,unique,primary key,foreign key,check

3、unique: allow null value  foreign key:allow null value

4、primary key: alter table (enable|disable) (novalidate|validate) primary key

5、pk immediate每条语句后检查， deferralbe生成nounique索引，在commit时统一检查约束

       SET CONSTRAINTS ALL DEFERRED;

       SET CONSTRAINT XXX DEFERRED;

 

6、子表外键应建索引，增加并发性

7、导数据的时候 2步：enable novalidate,enable validate

8、exceptions to table

 

数据字典：

dba_constraints
dba_cons_column