Oracle:基于函数的索引选择唯一性

Question

我必须保留历史记录,所以我使用的是is_deleted列,它可以有'Y'或'N'.但是对于任何is_deleted'N'的实例,我应该对(a,b,c)复合列进行任意的输入.

当我尝试创建基于函数的唯一索引时,我收到错误.

CREATE UNIQUE INDEX fn_unique_idx ON table1  (CASE WHEN is_deleted='N' then (id, name, type) end);

第1行的错误:ORA-00907:缺少右括号

请帮忙.

谢谢

Answer 1

你需要类似的东西

CREATE UNIQUE INDEX fn_unique_idx 
    ON table1 (CASE WHEN is_deleted='N' THEN id ELSE null END,
               CASE WHEN is_deleted='N' THEN name ELSE null END,
               CASE WHEN is_deleted='N' THEN type ELSE null END);

行动中的约束的一个例子

SQL> create table table1 (
  2    id number,
  3    name varchar2(10),
  4    type varchar2(10),
  5    is_deleted varchar2(1)
  6  );

Table created.

SQL> CREATE UNIQUE INDEX fn_unique_idx
  2      ON table1 (CASE WHEN is_deleted='N' THEN id ELSE null END,
  3                 CASE WHEN is_deleted='N' THEN name ELSE null END,
  4                 CASE WHEN is_deleted='N' THEN type ELSE null END);

Index created.

SQL> insert into table1 values( 1, 'Foo', 'Bar', 'N' );

1 row created.

SQL> insert into table1 values( 1, 'Foo', 'Bar', 'Y' );

1 row created.

SQL> insert into table1 values( 1, 'Foo', 'Bar', 'Y' );

1 row created.

SQL> insert into table1 values( 1, 'Foo', 'Bar', 'N' );
insert into table1 values( 1, 'Foo', 'Bar', 'N' )
*
ERROR at line 1:
ORA-00001: unique constraint (SCOTT.FN_UNIQUE_IDX) violated


SQL> insert into table1 values( 1, 'Foo', 'Zee', 'N' );

1 row created.