表中有多个约束:如何获取所有违规行为？

Question

我在Oracle中有一个表有几个约束.当我插入新记录并且并非所有约束都有效时,Oracle仅引发"第一个"错误.如何获取所有违反记录的行为？

CREATE TABLE A_TABLE_TEST (
  COL_1 NUMBER NOT NULL,
  COL_2 NUMBER NOT NULL,
  COL_3 NUMBER NOT NULL,
  COL_4 NUMBER NOT NULL
);

INSERT INTO A_TABLE_TEST values (1,null,null,2);

ORA-01400: cannot insert NULL into ("USER_4_8483C"."A_TABLE_TEST"."COL_2")

我想得到这样的东西:

Column COL_2: cannot insert NULL
Column COL_3: cannot insert NULL

This would be also sufficient:
Column COL_2: not valid
Column COL_3: not valid

当然我可以编写一个触发器并单独检查每一列,但我更喜欢约束而不是触发器,它们更容易维护,不需要手动编写代码.

任何的想法？

Answer 1

没有直接的方法来报告所有可能的约束违规.因为当Oracle在第一次违反约束时偶然发现时,无法进一步评估,语句将失败,除非该约束被延迟,或者该log errors子句已包含在DML语句中.但应该注意的是,log errors子句将无法捕获所有可能的约束违规,只记录第一个.

作为可能的方法之一是:

1. 创建exceptions表.它可以通过执行ora_home/rdbms/admin/utlexpt.sql脚本来完成.桌子的结构非常简单;
2. 禁用所有表约束;
3. 执行DML;
4. 使用exceptions into <<exception table name>>子句启用所有约束.如果您执行了utlexpt.sql脚本,那么将存储表异常的名称exceptions.

测试表:

create table t1(
  col1 number not null,
  col2 number not null,
  col3 number not null,
  col4 number not null
);

尝试执行一个insert声明:

insert into t1(col1, col2, col3, col4)
  values(1, null, 2, null);

Error report -
SQL Error: ORA-01400: cannot insert NULL into ("HR"."T1"."COL2")

禁用所有表的约束:

alter table T1 disable constraint SYS_C009951;     
alter table T1 disable constraint SYS_C009950;     
alter table T1 disable constraint SYS_C009953;     
alter table T1 disable constraint SYS_C009952; 

尝试再次执行以前失败的insert语句:

insert into t1(col1, col2, col3, col4)
  values(1, null, 2, null);

1 rows inserted.

commit;

现在,启用表的约束并在exceptions表中存储异常(如果有):

alter table T1 enable constraint SYS_C009951 exceptions into exceptions; 
alter table T1 enable constraint SYS_C009950 exceptions into exceptions; 
alter table T1 enable constraint SYS_C009953 exceptions into exceptions; 
alter table T1 enable constraint SYS_C009952 exceptions into exceptions; 

检查exceptions表格:

column row_id     format a30;
column owner      format a7;
column table_name format a10;
column constraint format a12;

select *
  from exceptions 

ROW_ID                         OWNER   TABLE_NAME CONSTRAINT 
------------------------------ ------- -------    ------------
AAAWmUAAJAAAF6WAAA             HR      T1         SYS_C009951  
AAAWmUAAJAAAF6WAAA             HR      T1         SYS_C009953

违反了两个限制因素.要查找列名,只需user_cons_columns参考数据字典视图:

column table_name   format a10;
column column_name  format a7;
column row_id       format a20;

select e.table_name
     , t.COLUMN_NAME
     , e.ROW_ID
  from user_cons_columns t
  join exceptions e
    on (e.constraint = t.constraint_name)


TABLE_NAME COLUMN_NAME ROW_ID             
---------- ----------  --------------------
T1         COL2        AAAWmUAAJAAAF6WAAA   
T1         COL4        AAAWmUAAJAAAF6WAAA

上面的查询为我们提供了列名和有问题记录的rowid.手头有rowid,找到导致约束违规的记录,修复它们,再次重新启用约束应该没有问题.

以下是用于生成alter table用于启用和禁用约束的语句的脚本:

column cons_disable format a50
column cons_enable format a72

select 'alter table ' || t.table_name || ' disable constraint '|| 
        t.constraint_name || ';' as cons_disable
     , 'alter table ' || t.table_name || ' enable constraint '|| 
        t.constraint_name || ' exceptions into exceptions;' as cons_enable
  from user_constraints t
where t.table_name = 'T1'
order by t.constraint_type

Answer 2

与此同时，我找到了一个使用延迟约束的精益解决方案：

CREATE TABLE A_TABLE_TEST (
  COL_1 NUMBER NOT NULL DEFERRABLE INITIALLY DEFERRED,
  COL_2 NUMBER NOT NULL DEFERRABLE INITIALLY DEFERRED,
  COL_3 NUMBER NOT NULL DEFERRABLE INITIALLY DEFERRED,
  COL_4 NUMBER NOT NULL DEFERRABLE INITIALLY DEFERRED
);

INSERT INTO A_TABLE_TEST values (1,null,null,2);    

DECLARE
    CHECK_CONSTRAINT_VIOLATED EXCEPTION;
    PRAGMA EXCEPTION_INIT(CHECK_CONSTRAINT_VIOLATED, -2290);

    REF_CONSTRAINT_VIOLATED EXCEPTION;
    PRAGMA EXCEPTION_INIT(REF_CONSTRAINT_VIOLATED , -2292);


    CURSOR CheckConstraints IS
    SELECT TABLE_NAME, CONSTRAINT_NAME, COLUMN_NAME
    FROM USER_CONSTRAINTS
        JOIN USER_CONS_COLUMNS USING (TABLE_NAME, CONSTRAINT_NAME)
    WHERE TABLE_NAME = 'A_TABLE_TEST'
        AND DEFERRED = 'DEFERRED'
        AND STATUS = 'ENABLED';
BEGIN
    FOR aCon IN CheckConstraints LOOP
    BEGIN
        EXECUTE IMMEDIATE 'SET CONSTRAINT '||aCon.CONSTRAINT_NAME||' IMMEDIATE';
    EXCEPTION
        WHEN CHECK_CONSTRAINT_VIOLATED OR REF_CONSTRAINT_VIOLATED  THEN
        DBMS_OUTPUT.PUT_LINE('Constraint '||aCon.CONSTRAINT_NAME||' at Column '||aCon.COLUMN_NAME||' violated');
    END;
    END LOOP;
END;

它适用于任何检查约束（不仅仅是NOT NULL）。检查FOREIGN KEY约束也应该有效。

添加/修改/删除约束不需要任何进一步的维护。