在删除 MySQL 中的重复项时，DELETE 的目标 table 不是 updatable

Question

我正在使用 windows 函数 Row_Number() 编写此查询，它将找出重复项，我正尝试 delete 这些重复项。

为此，我编写了 CTE 并包含 window 函数并尝试删除重复行。但是，我收到错误消息说删除不可更新。

select * from housingdata;
.
.
.
with rownumcte as (
select * ,row_number() over (partition by ParcelID, PropertyAddress, 
SalePrice,saledate,LegalReference  order by UniqueID) as rownum
from housingdata)
delete 
from rownumcte
where rownum>1;

如果我使用 select 而不是 delete，我将得到以下包含重复项的输出，即 104 rows

Answer 1

是的，CTE 对很多事情都非常有用，但对您的目的却不是。

改用 INNER JOIN.

CREATE TABLE housingdata (UniqueID int, 
ParcelID int
, PropertyAddress varchar(50)
, 
SalePrice DECIMAL(10,2)
,saledate Date
,LegalReference int)

INSERT INTO housingdata VALUES (1,1,'test',1.1, NOW(), 1),(2,1,'test',1.1, NOW(), 1)

delete hd
FROM housingdata hd INNER JOIN

(
select UniqueID ,row_number() over (partition by ParcelID, PropertyAddress, 
SalePrice,saledate,LegalReference  order by UniqueID) as rownum
from housingdata) t1 ON hd.UniqueID = t1.UniqueID 
WHERE t1.rownum>1;

SELECT * FROM housingdata

UniqueID | ParcelID | PropertyAddress | SalePrice | saledate   | LegalReference
-------: | -------: | :-------------- | --------: | :--------- | -------------:
       1 |        1 | test            |      1.10 | 2022-02-25 |              1

db<>fiddle here

更新

您也可以使用已加入的 CTE table

with rownumcte as (
select UniqueID ,row_number() over (partition by ParcelID, PropertyAddress, 
SalePrice,saledate,LegalReference  order by UniqueID) as rownum
from housingdata)
delete hd
from housingdata hd INNER JOIN rownumcte r ON hd.UniqueID = r.UniqueID
where rownum>1;

SELECT * FROM housingdata

UniqueID | ParcelID | PropertyAddress | SalePrice | saledate   | LegalReference
-------: | -------: | :-------------- | --------: | :--------- | -------------:
       1 |        1 | test            |      1.10 | 2022-02-25 |              1

db<>fiddle here

在删除 MySQL 中的重复项时，DELETE 的目标 table 不是 updatable

Target table of DELETE is not updatable while deleting duplicates in MySQL

mysql

window-functions

更新