删除重复在SQL和相应地修改关系表(deleting duplicates in sql and m

我有三个表：menu_tab有列（menu_id，menu_description）item_tab有列（ITEM_ID，ITEM_NAME，ITEM_DESCRIPTION，ITEM_PRICE）menu_has_item有列{（menu_tab_menu_id --->这是外键menu_id（PK中menu_tab）），item_tab_item_id - - 这是外键ITEM_ID（在item_tab PK））4

会有2种重复的将要遇到的1）物品在同一menu_description 2）项目复制在不同的菜单说明重复

例如：两个香鸡的午餐菜单。 在午餐的一个鸡肉三明治，另一个在晚宴菜单_description

menu_tab    
menu_id menu_description
1        lunch
2        dinner
3        Specials


item_tab        
item_id item_description    
1       b 
2       d   
3       g   
4       x   
5       g          delete g
6       d   
7       e   
8       b          delete b
9       x   



menu_has_tab

menu_tab_menu_id item_tab_item_id
1 ............................ 1
1 ............................ 2
1 ............................ 3
1 ............................ 4
2 ............................ 5由3取代
2 ............................ 6
3 ............................ 7
3 ............................ 8由1代替
3 ............................ 9

我怎样去除重复之后被替换的值更新我的menu_has_item？

Answer 1:

begin
  for x in (
            -- find duplicate items
            select *
              from (select rowid row_id,
                           item_id,
                           item_description,
                           row_number() over(partition by item_description order by
                           item_description) row_no
                       from item_tab)
            where row_no > 1) loop
-- replaceing duplicate Items
    update menu_has_item 
    set menu_has_item.item_tab_item_id =
           ( select item_id
              from (select item_id,
                           row_number() over(partition by item_description order by
                           item_description) row_no
                       from item_tab where 
                       item_tab.item_description = x.item_description)
             where row_no = 1)
   where menu_has_item .item_tab_item_id = x.item_id;
-- deleting duplicate items
     delete item_tab where rowid = x.row_id;
  end loop;
-- commit;
end;

Answer 2:

首先你需要更换你的重复与新价值menu_tab

merge into menu_tab dest
using (select *
         from (select item_id, min(item_id) over(partition by item_description) as new_item_id from item_tab)
        where item_id != new_item_id) src
on (dest.item_tab_item_id = src.item_id)
when matched then
    update set dest.item_tab_item_id = new_item_id;

之后，你需要删除从项目表副本，你可以找到脚本有http://sprogram.com.ua/en/articles/oracle-delete-duplicate-record

UPS您标记问题如PLSQL和我mistakelly认为你有关甲骨文公司的，对不起。 但我supose在MySQL存在合并声明好运

Answer 3:

我这样做是为了我的表溃败（RoutID，SourceCityID，DestCityID）和表格（FormID，RoutID，...）我删除重复击溃从表溃败和形式表更新RoutID
首先得到由列分组重复的行，美想要比较重复

(SELECT * FROM
    Rout,
    (SELECT MIN(RoutID) MinRoutID
    FROM Rout,
        (SELECT SourceCityID,DestCityID
        FROM Rout
        GROUP BY SourceCityID,DestCityID
        HAVING count(*) > 1) AS Duplicates
    WHERE Rout.SourceCityID=Duplicates.SourceCityID AND Rout.DestCityID=Duplicates.DestCityID
    GROUP BY Rout.SourceCityID,Rout.DestCityID)AS MRCols
WHERE RoutID=MinRoutID)AS DuplicateGroup

然后得到不进行分组，并与列的所有重复的行会重复进行比较

(SELECT RoutID,Rout.SourceCityID,Rout.DestCityID FROM Rout,
    (SELECT SourceCityID,DestCityID
    FROM Rout
    GROUP BY SourceCityID,DestCityID
    HAVING count(*) > 1)AS Duplicates
WHERE Rout.SourceCityID=Duplicates.SourceCityID AND Rout.DestCityID=Duplicates.DestCityID)AS DuplicateDetail

然后更新表单TBL象下面这样：

UPDATE Form SET RoutID=DuplicateGroup.RoutID
FROM
    Form,
    (SELECT * FROM
        Rout,
        (SELECT MAX(RoutID) MinRoutID
        FROM Rout,
            (SELECT SourceCityID,DestCityID
            FROM Rout
            GROUP BY SourceCityID,DestCityID
            HAVING count(*) > 1) AS Duplicates
        WHERE Rout.SourceCityID=Duplicates.SourceCityID AND Rout.DestCityID=Duplicates.DestCityID
        GROUP BY Rout.SourceCityID,Rout.DestCityID)AS MRCols
    WHERE RoutID=MinRoutID)AS DuplicateGroup
    ,
    (SELECT RoutID,Rout.SourceCityID,Rout.DestCityID FROM Rout,
        (SELECT SourceCityID,DestCityID
        FROM Rout
        GROUP BY SourceCityID,DestCityID
        HAVING count(*) > 1)AS Duplicates
    WHERE Rout.SourceCityID=Duplicates.SourceCityID AND Rout.DestCityID=Duplicates.DestCityID)AS DuplicateDetail
WHERE
    Form.RoutID=DuplicateDetail.RoutID AND
    DuplicateGroup.SourceCityID=DuplicateDetail.SourceCityID
    AND DuplicateGroup.DestCityID=DuplicateDetail.DestCityID

现在删除溃败以表格形式的arent行

DELETE FROM Rout WHERE RoutID NOT IN(SELECT DISTINCT RoutID FROM Form)

文章来源: deleting duplicates in sql and modifying relationship table accordingly