oracle - Oracle：如何用 case when 制定复杂的约束

Question

以下条件约束根本不起作用。是否有可能以一种可行的方式制定？

ALTER TABLE eni_trasc_voci_pwr_fatt
ADD CONSTRAINT tvp_constraint_1 CHECK (
CASE WHEN TVP_CODICE_ASSOGGETAMEN = '-' THEN tvp_regione IS NULL
END);

Answer 1

Try the following:

ALTER TABLE eni_trasc_voci_pwr_fatt
ADD CONSTRAINT tvp_constraint_1 CHECK (
CASE WHEN TVP_CODICE_ASSOGGETAMEN = '-' THEN tvp_regione else null end IS NULL);

Answer 2

看起来你想要这里的逻辑含义（“如果 X 则 Y”），这在逻辑上等同于“（不是 X）或 Y”。CASE 用于创建有限映射。

您的约束应该类似于

TVP_CODICE_ASSOGGETAMEN != '-' OR TVP_REGIONE IS NULL

Answer 3

我认为你可以在没有 case 语句的情况下做你想做的事：

create table t1 (c1 varchar2(10), c2 varchar2(10));

alter table t1 add constraint t1_chk1 check ( (c1 = '-' and c2 is null) or (c1 != '-' and c2 is not null) );

现在尝试插入一些值：

SQL> insert into t1 values ('-', 'reject');
insert into t1 values ('-', 'reject')  
*
ERROR at line 1:
ORA-02290: check constraint (SODONNEL.T1_CHK1) violated


SQL>
SQL> insert into t1 values ('-', null);

1 row created.

SQL>
SQL> insert into t1 values ('a', null);
insert into t1 values ('a', null)
*
ERROR at line 1:
ORA-02290: check constraint (SODONNEL.T1_CHK1) violated


SQL>
SQL> insert into t1 values ('a', 'accept');

1 row created.