Question

CREATE OR REPLACE PROCEDURE disable_all_constraints
  (p_owner      IN VARCHAR2,
   p_table_name IN VARCHAR2)
IS
CURSOR check_status IS
      (SELECT status
       FROM all_constraints
       WHERE owner = p_owner 
       AND   table_name = p_table_name );
v_status     VARCHAR2(10);
BEGIN
  OPEN check_status;
  FETCH check_status
  INTO v_status;
  IF (check_status %NOTFOUND) 
  THEN
  DBMS_OUTPUT.PUT_LINE('No Constraints added to the table, give me another table to process!');
  ELSE
  FOR cur IN (SELECT owner, constraint_name , table_name 
              FROM   all_constraints
              WHERE  owner = p_owner
              AND    table_name = p_table_name) 
      LOOP
      EXECUTE IMMEDIATE 'ALTER TABLE '||cur.owner||'.'||cur.table_name||' MODIFY CONSTRAINT '||cur.constraint_name||' DISABLE CASCADE ';
      END LOOP;
  END IF;
  CLOSE check_status;
  SELECT DISTINCT status
  INTO   v_status 
  FROM   all_constraints
  WHERE  owner = p_owner
  AND table_name = p_table_name;
  IF  v_status = 'DISABLED'      
  THEN 
  DBMS_OUTPUT.PUT_LINE('All related constraints disable succesufully!');
  ELSE 
  DBMS_OUTPUT.PUT_LINE('Something went wrong, but that is impossible!');
  END IF; 
END;

所以我写了上面的文章。我测试了它，我认为它的工作做得很好。但我的问题是，它有多正确或多么糟糕？它可以以更容易和最佳的方式完成吗？感谢。

Answer 1

你这样做的方式没有任何本质上的错误，但是存在许多潜在问题和一些不必要的代码。

你的第一个光标是不必要的，无论如何你要循环遍历ALL_CONSTRAINTS - 如果你没有进入循环那么表没有约束
您可以尝试禁用已禁用的约束 - 您只需选择当前启用的那些约束。
如果有多个状态，那么总是总是的最终选择将会始终失败，因为您将获得TOO_MANY_ROWS异常（用于返回多行）。这意味着永远不会输入您的最终ELSE语句。

高度不可能在没有引发异常的情况下禁用约束。我甚至不打算进行最后的检查。

更一般地说，向屏幕输出信息很少有意义。它需要有人阅读它。如果一切正常，或者在发生错误时引发异常，那么通常会更好。

我会大量简化为类似下面的内容，它只是循环遍历非禁用的约束并禁用它们。

create or replace procedure disable_all_constraints ( p_owner in varchar2 , p_table_name in varchar2 ) is begin for cur in ( select owner || '.' || table_name as object , constraint_name from all_constraints where owner = p_owner and table_name = p_table_name and status <> 'DISABLED' ) loop execute immediate 'alter table ' || cur.object || ' modify constraint ' || cur.constraint_name || ' disable cascade'; end loop; end;

如果您觉得必须进行额外的检查和打印，可以更干净地完成：

create or replace procedure disable_all_constraints ( p_owner in varchar2 , p_table_name in varchar2 ) is l_has_constraint boolean := False; l_ct number; begin for cur in ( select owner || '.' || table_name as object , constraint_name from all_constraints where owner = p_owner and table_name = p_table_name and status <> 'DISABLED' ) loop l_has_constraint := True; execute immediate 'alter table ' || cur.object || ' modify constraint ' || cur.constraint_name || ' disable cascade'; end loop; if not l_has_constraint then dbms_output.put_line('No Constraints added to the table.'); else select count(*) into l_ct from all_constraints where owner = p_owner and table_name = p_table_name and status <> 'DISABLED' ; if l_ct = 0 then dbms_output.put_line('All related constraints disable successfully'); else dbms_output.put_line('Something went wrong, but that is impossible'); end if; end if; end;

使用Oracle PL / SQL禁用表中的所有相关约束

1 个答案: