Oracle约束状态,Oracle约束的4种状态小结

约束的4种状态：

disable novalidate 既不会约束新增数据也不会验证已有数据，等同于disable

enable novalidate 约束新增数据但不会验证已有数据

disable validate 约束新增数据但不会验证已有数据，启用后禁止DML

enable validate 约束新增数据并验证已有数据，等同于enable

扩展解释：

disable / enable 针对新增数据(对于唯一性约束，enable会自动创建唯一性索引，disable会自动drop索引)；

novalidate / validate 针对已有数据。

测试：

Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0

Connected as system

SQL> drop table dept2;

Table dropped

SQL> create table dept2 as select * from scott.dept;

Table created

SQL> select * from dept2 order by deptno;

DEPTNO DNAME LOC

------ -------------- -------------

10 ACCOUNTING NEW YORK

20 RESEARCH DALLAS

30 SALES CHICAGO

40 OPERATIONS BOSTON

SQL> alter table dept2 add constraint dept2_u1 unique(deptno);

Table altered

SQL> select index_name,table_name,uniqueness from dba_indexes where index_name = 'DEPT2_U1';

INDEX_NAME TABLE_NAME UNIQUENESS

------------------------------ ------------------------------ ----------

DEPT2_U1 DEPT2 UNIQUE

SQL> select constraint_name,status,validated from dba_constraints where constraint_name = 'DEPT2_U1';

CONSTRAINT_NAME STATUS VALIDATED

------------------------------ -------- -------------

DEPT2_U1 ENABLED VALIDATED

SQL> insert into dept2(deptno) values(10);

insert into dept2(deptno) values(10)

ORA-00001: unique constraint (SYSTEM.DEPT2_U1) violated

SQL> select * from dept2 order by deptno;

DEPTNO DNAME LOC

------ -------------- -------------

10 ACCOUNTING NEW YORK

20 RESEARCH DALLAS

30 SALES CHICAGO

40 OPERATIONS BOSTON

SQL> alter table dept2 modify constraint dept2_u1 disable novalidate;

Table altered

SQL> select index_name,table_name,uniqueness from dba_indexes where index_name = 'DEPT2_U1';

INDEX_NAME TABLE_NAME UNIQUENESS

------------------------------ ------------------------------ ----------

(disable自动移除索引)

SQL> select constraint_name,status,validated from dba_constraints where constraint_name = 'DEPT2_U1';

CONSTRAINT_NAME STATUS VALIDATED

------------------------------ -------- -------------

DEPT2_U1 DISABLED NOT VALIDATED

SQL> insert into dept2(deptno) values(10);

1 row inserted

SQL> select * from dept2 order by deptno;

DEPTNO DNAME LOC

------ -------------- -------------

10 ACCOUNTING NEW YORK

10

20 RESEARCH DALLAS

30 SALES CHICAGO

40 OPERATIONS B