启用oracle约束的问题

如何解决启用oracle约束的问题

| 我想尝试几天来禁用所有表的约束，插入数据并启用约束。它可以工作，但是我做了一些测试，当我插入不尊重外键的行时，启用约束时没有错误消息。我所看到的是该约束未得到验证。 这是要禁用的代码

begin    
     BEGIN
      FOR rec IN ( SELECT constraint_name,table_name FROM user_constraints WHERE  constraint_type = \'R\' OR constraint_type = \'P\' )
      LOOP
        BEGIN
        EXECUTE IMMEDIATE \'alter table \'||rec.table_name||\' disable constraint \'||rec.constraint_name;
         EXCEPTION WHEN OTHERS THEN
             dbms_output.put_line( \'ERROR: alter table \'||rec.table_name||\' DISABLE constraint \'||rec.constraint_name||\';\' );
        END;      
      END LOOP;
      DBMS_OUTPUT.PUT_LINE(\'CONSTRAINTS DISABLED\');
     END;
     BEGIN
     FOR rec IN ( SELECT trigger_name FROM user_triggers WHERE TRIGGER_NAME NOT LIKE \'BIN$%\' )
      LOOP
            EXECUTE IMMEDIATE \'alter trigger \'||rec.trigger_name||\' disable\';
      END LOOP;
    END;
    DBMS_OUTPUT.PUT_LINE(\'TRIGGERS DISABLED\');
end;    
/

这是启用的代码

begin
  BEGIN
      FOR rec IN ( SELECT constraint_name,table_name FROM user_constraints where status = \'DISABLED\' and constraint_type = \'R\' OR constraint_type = \'P\' )
      LOOP
        BEGIN
          EXECUTE IMMEDIATE \'alter table \'||rec.table_name||\' enable constraint \'||rec.constraint_name;
          dbms_output.put_line(\'alter table \'||rec.table_name||\' enable constraint \'||rec.constraint_name);
        EXCEPTION
          WHEN OTHERS THEN
            dbms_output.put_line(\'ERROR: alter table \'||rec.table_name||\' enable constraint \'||rec.constraint_name||\' ;\' );

        END;
      END LOOP;
    END;
                DBMS_OUTPUT.PUT_LINE(\'CONSTRAINTS ENABLED\');
    BEGIN
      FOR rec IN ( SELECT trigger_name FROM user_triggers WHERE TRIGGER_NAME NOT LIKE \'BIN$%\' )
      LOOP
          EXECUTE IMMEDIATE \'alter trigger \'||rec.trigger_name||\' enable\';
      END LOOP;
    END;
                DBMS_OUTPUT.PUT_LINE(\'TRIGGERS ENABLED\');
END;

我不知道如何最后检查所有约束并在不起作用时进行回滚。     

解决方法

        首先，您的代码捕获了无法启用约束时引发的错误，并且抛出该错误而不是重新引发该错误。那几乎总是一个错误。如果您不想忽略启用约束失败的事实，则需要类似

FOR rec IN ( SELECT constraint_name,table_name 
               FROM user_constraints 
              where status = \'DISABLED\' 
                and constraint_type = \'R\' 
                 OR constraint_type = \'P\' )
LOOP
  BEGIN
    l_sql_stmt := \'alter table \'||rec.table_name||
                  \' enable constraint \' || rec.constraint_name;
    dbms_output.put_line( l_sql_stmt );
    EXECUTE IMMEDIATE l_sql_stmt;
  EXCEPTION
    WHEN OTHERS THEN
      dbms_output.put_line(\'ERROR: \' || l_sql_stmt );
      raise; -- re-raise the exception
  END;
END LOOP;

由于ALTER TABLE是DDL，因此无法回滚。如果在启用一个约束时遇到错误，则无法回滚所有先前约束的启用。 根据您的最新更新，听起来您可能根本不想禁用和启用约束。您可能只想创建可延迟的约束。

SQL> create table foo (
  2    col1 number
  3  );

Table created.

SQL> ed
Wrote file afiedt.buf

  1  alter table foo
  2    add constraint pk_foo
  3        primary key( col1 )
  4*       deferrable
SQL> /

Table altered.

通常，它的行为类似于任何其他主键约束

SQL> insert into foo values( 1 );

1 row created.

SQL> insert into foo values( 1 );
insert into foo values( 1 )
*
ERROR at line 1:
ORA-00001: unique constraint (SCOTT.PK_FOO) violated


SQL> rollback;

Rollback complete.

但是，如果您推迟约束，则直到您提交该约束，该约束才会被验证。并且，如果在事务结束时违反了约束，则事务将回滚。

SQL> alter session set constraints = deferred;

Session altered.

SQL> select * from foo;

no rows selected

SQL> insert into foo values( 1 );

1 row created.

SQL> insert into foo values( 1 );

1 row created.

SQL> insert into foo values( 1 );

1 row created.

SQL> commit;
commit
*
ERROR at line 1:
ORA-02091: transaction rolled back
ORA-00001: unique constraint (SCOTT.PK_FOO) violated