是否有替代方法在pl / sql for循环中说'next'？

Question

所以我有一个处理ID列表的for循环，并且有一些相当复杂的事情要做。没有涉及所有丑陋的细节，基本上就是这样：

    DECLARE
      l_selected APEX_APPLICATION_GLOBAL.VC_ARR2;

      ...snip...
    BEGIN

      -- get the list ids
      l_selected := APEX_UTIL.STRING_TO_TABLE(:P4_SELECT_LIST);
      -- process each in a nice loop
      FOR i IN 1..l_selected.count 
      LOOP
        -- do some data checking stuff...

        -- here we will look for duplicate entries, so we can noop if duplicate is found
        BEGIN
          SELECT county_id INTO v_dup_check FROM org_county_accountable
          WHERE organization_id = :P4_ID AND county_id = v_county_id;
          -- NEXT;! NOOP;! but there is no next!
        EXCEPTION WHEN NO_DATA_FOUND THEN
          dbms_output.put_line('no dups found, proceeding');
        END;
        -- here we have code we only want to execute if there are no dupes already
        IF v_dup_check IS NULL THEN
          -- if not a duplicate record, proceed...

        ELSE
          -- reset duplicate check variable
          v_dup_check := NULL;
        END;
      END LOOP;
    END;

我通常如何处理它是通过选择一个值，然后将以下代码包装在IF语句中检查以确保重复的检查变量为NULL。但它很烦人。我只想说下一个;或NOOP;或者其他的东西。特别是因为我已经必须捕获NO_DATA_FOUND异常。我想我可以给Oracle写一封信，但我很好奇别人如何处理这个问题。

我也可以将它包装在一个函数中，但我正在寻找一些更清洁/更简单的东西。

Answer 1

也可以计算行数（参见Pourquoi Litytestdata），但您也可以在 when_no_data_found异常块中执行您想要的操作。

declare 
  l_selected    apex_application_global.vc_arr2;
  l_county_id   org_county_accountable.count_id%type;
begin
  l_selected := apex_util.string_to_table(:p4_select_lst);
  for i in l_selected.first..l_selected.last loop
    begin
      select count_id
      into   l_county_id
      from   org_county_accountable
      where  organization_id = :p4_id
      and    county_id       = v_county_id;
    exception
      when no_data_found then 
        -- here we have code we only want to execute if there are no dupes already
        -- if not a duplicate record, proceed...
    end;
  end loop;
end;

Answer 2

Oracle 11g增加了C风格的“继续”功能。循环构造到PL / SQL，在语法上听起来就像你正在寻找的那样。

为了您的目的，为什么不在进入循环之前消除重复项？这可以通过使用表函数查询l_selected，然后过滤掉您不想要的记录而不是迭代每个值来完成。有点像...

declare

l_selected APEX_APPLICATION_GLOBAL.VC_ARR2;

cursor no_dups_cur (p_selected APEX_APPLICATION_GLOBAL.VC_ARR2) is 
  select * from (
  select selected.*, 
         count(*) over (partition by county_id) cnt -- analytic to find counts grouped by county_id
    from table(p_selected) selected -- use table function to treat VC_ARR2 like a table 
    ) where cnt = 1 -- remove records that have duplicate county_ids
    ;

begin

l_selected := APEX_UTIL.STRING_TO_TABLE(:P4_SELECT_LIST);

for i in no_dups_cur(l_selected) loop

  null; -- do whatever to non-duplicates 

end loop;

end;

只需用逻辑代替“重复”即可。与你自己的（你的例子中没有足够的信息真正回答那部分）

Answer 3

而不是捕获 NO_DATA_FOUND ，如何将匹配条目的数量选择到一个变量中，比如说 l_count ，然后继续这个计数是否为零？如下所示：

    DECLARE
      l_selected APEX_APPLICATION_GLOBAL.VC_ARR2;
      l_count    INTEGER;

      ...snip...
    BEGIN

      -- get the list ids
      l_selected := APEX_UTIL.STRING_TO_TABLE(:P4_SELECT_LIST);
      -- process each in a nice loop
      FOR i IN 1..l_selected.count 
      LOOP
        -- do some data checking stuff...

        -- here we will count duplicate entries, so we can noop if duplicate is found
        SELECT COUNT(*) INTO l_count FROM org_county_accountable
         WHERE organization_id = :P4_ID AND county_id = v_county_id;
        IF l_count = 0 THEN
          -- here we have code we only want to execute if there are no dupes already
          -- if not a duplicate record, proceed...

        END IF;
      END LOOP;
    END;

Answer 4

<xmp>
<<next_loop>>
loop
...
...
if ....
then
   goto next_loop;

</xmp>

Answer 5

这是GOTO语句可能有用的情况。请参阅 Oracle文档控制结构，看看如何做到这一点。此外，您可能希望在此处搜索以了解如何查询记录的存在。运行查询并等待异常不是最佳选择。

Answer 6

另一种方法 - 将支票转换为本地功能：

DECLARE
  l_selected APEX_APPLICATION_GLOBAL.VC_ARR2;

  ...snip...
  FUNCTION dup_exists 
     ( p_org_id org_county_accountable.organization_id%TYPE
     , p_county_id org_county_accountable.county_id%TYPE
     ) RETURN BOOLEAN 
  IS
    v_dup_check org_county_accountable.county_id%TYPE;
  BEGIN
    SELECT county_id INTO v_dup_check FROM org_county_accountable
    WHERE organization_id = p_org_id AND county_id = p_county_id;
    RETURN TRUE;
  EXCEPTION WHEN NO_DATA_FOUND THEN
    RETURN FALSE;
  END;
BEGIN

  -- get the list ids
  l_selected := APEX_UTIL.STRING_TO_TABLE(:P4_SELECT_LIST);
  -- process each in a nice loop
  FOR i IN 1..l_selected.count
  LOOP
    -- do some data checking stuff...

    -- here we have code we only want to execute if there are no dupes already
    IF NOT dup_exists (:P4_ID, v_county_id) THEN
      -- if not a duplicate record, proceed...

    END;
  END LOOP;
END;

当然，如果您愿意，可以重写本地函数以使用count方法：

  FUNCTION dup_exists 
     ( p_org_id org_county_accountable.organization_id%TYPE
     , p_county_id org_county_accountable.county_id%TYPE
     ) RETURN BOOLEAN 
  IS
    l_count INTEGER;
  BEGIN
     SELECT COUNT(*) INTO l_count 
       FROM org_county_accountable
      WHERE organization_id = p_org_id AND county_id = p_county_id;
     RETURN (l_count > 0);
  END;

Answer 7

另一种方法是引发和处理用户定义的异常：

DECLARE
  l_selected APEX_APPLICATION_GLOBAL.VC_ARR2;
  duplicate_org_county EXCEPTION;

  ...snip...
BEGIN

  -- get the list ids
  l_selected := APEX_UTIL.STRING_TO_TABLE(:P4_SELECT_LIST);
  -- process each in a nice loop
  FOR i IN 1..l_selected.count 
  LOOP
    BEGIN
      -- do some data checking stuff...

      -- here we will look for duplicate entries, so we can noop if duplicate is found
      BEGIN
        SELECT county_id INTO v_dup_check FROM org_county_accountable
        WHERE organization_id = :P4_ID AND county_id = v_county_id;
        RAISE duplicate_org_county;
      EXCEPTION WHEN NO_DATA_FOUND THEN
        dbms_output.put_line('no dups found, proceeding');
      END;
      -- here we have code we only want to execute if there are no dupes already

    EXCEPTION
      WHEN duplicate_org_county THEN NULL;
    END;
  END LOOP;
END;

我通常不会这样做，但如果有六个理由跳转到下一条记录，这可能比多个嵌套的IF更好。

Answer 8

我知道这是一个老人，但我不禁注意到上面的答案都没有考虑到光标属性：

游标有四个属性：ISOPEN，FOUND，NOTFOUND和ROWCOUNT。可以使用％分隔符访问这些属性以获取有关游标状态的信息。

游标属性的语法是：

cursor_name%attribute

其中cursor_name是显式游标的名称。

因此，在这种情况下，您可以使用ROWCOUNT（表示到目前为止提取的行数），例如：

declare 
   aux number(10) := 0;
   CURSOR cursor_name is select * from table where something;
begin
     select count(*) into aux from table where something;
     FOR row IN cursor_name LOOP
        IF(aux > cursor_name%ROWCOUNT) THEN 'do something is not over';
        ELSE 'do something else';
        END IF;
     END LOOP;
end;