刪除重復項並在SQL Server中保留一個條件

Question

我正在使用SQL Server。

我的桌子設計如下：

ID bigint
Number varchar(50)
Processed int

我在“號碼”列中有很多重復項

我想刪除所有重復的數字，並保留已where processed=1的數字where processed=1

例如，如果我有

Number --- Processed
 111   ---   0
 111   ---   0
 111   ---   1

我要刪除所有並保留最后一個

任何幫助，將不勝感激

Answer 1

這是一種方法：

with todelete as (
      select t.*,
             row_number() over (partition by number order by processed desc) as seqnum
      from table t
     )
delete from todelete
    where seqnum > 1;

row_number() ，將處理為優先級。 邏輯確保即使processed = 1 ，也只剩下一行。

Answer 2

如果您只是嘗試刪除數字等於111且已處理的數字不等於1的行，則可以執行以下操作：

delete from <table>
where
 Number = 111 and
 Processed <> 1

假設ID是連續的，並且您想保留每個數字的最后一行，則可以執行以下操作：

delete from <table> t
left join (
    select
        MAX(ID) filter_ID
    from <table>
    group by
        Number
) filter on
    t.ID = filter.filter_ID
where
    filter.filter_ID is null

保持每個編號至少保留一行，優先於已處理= 1

delete from <table> t
left join (
    select
    ID
    from (
        select
            ROW_NUMBER() OVER (
                PARTITION BY 
                    Number
                ORDER BY
                    Processed DESC,
                    ID DESC
            ) last_R,
            ID
        from <table>
    ) filter
    where
        last_R = 1
) filter on
    t.ID = filter.filter_ID
where
    filter.filter_ID is null

Answer 3

這是解決該問題的方法：

DECLARE @NUM VARCHAR(50)
DECLARE @TAB TABLE
(
    NUMBER VARCHAR(50)
)

INSERT INTO @TAB
SELECT number, from <table> where processed = 0 GROUP BY number HAVING COUNT(number) > 1

DECLARE @IDToKEEP TABLE
(
    id INT
)

WHILE (SELECT COUNT(*) FROM @TAB) > 0
BEGIN
    SELECT TOP 1 @NUM = number FROM @TAB

    INSERT INTO @IDToKEEP
    SELECT TOP 1 id FROM <table> WHERE number = @NUM

    DELETE FROM @TAB WHERE number = @NUM
END

DELETE FROM <table> WHERE processed = 0 AND number IN (SELECT number FROM @TAB) AND id NOT IN (SELECT id FROM @IDToKEEP)