删除重复的行集

Question

数据

CREATE TABLE #tbl_LinkedInvoices(
    InvoiceNbr              varchar(50)
,   AssociatedInvoiceNbr    varchar(50)
,   RowNbr                  int
,   AssociatedRowNbr        int
)
INSERT INTO #tbl_LinkedInvoices(
        InvoiceNbr, AssociatedInvoiceNbr, RowNbr, AssociatedRowNbr)
VALUES 
    ('A0001', 'A1001', 1, 4),
    ('A0002', 'A2002', 2, 5),
    ('A0002', 'A3002', 3, 6),
    ('A1001', 'A0001', 4, 1),
    ('A2002', 'A0002', 5, 2),
    ('A3002', 'A0002', 6, 3)

    SELECT * FROM #tbl_LinkedInvoices

Challenge/Goal

tbl_LinkedInvoices 用于标识 AssociatedInvoiceNbrs b 和 InvoiceNbr a 链接到。因此，自 (a, b) = (b,a) 以来，一个集合可以在 table 中出现多次。为了解决这些重复出现的问题，添加了 RowNbr 和 AssociatedRowNbr 字段以提供分组序列。

根据识别出的重复行，删除重复行，保留 table 中的单个唯一记录。当前脚本产生错误，希望有更好的方法来编写查询。

脚本

使用计数器检查重复行是否仍然存在，如果它确实删除该行，直到FALSE。

DECLARE @RowCounter int
DECLARE @RemoveRow int
SET @RowCounter = 1



IF EXISTS (SELECT 
              RowNbr
           FROM #tbl_LinkedInvoices WHERE RowNbr = (SELECT AssociatedRowNbr FROM #tbl_LinkedInvoices)
)
BEGIN
   SET @RemoveRow = (SELECT RowNbr FROM #tbl_LinkedINvoices
                     WHERE RowNbr = (
                            SELECT AssociatedRowNbr FROM #tbl_LinkedInvoices WHERE RowNbr =@RowCounter ))
    BEGIN
        DELETE FROM #tbl_LinkedInvoices
        WHERE
        RowNbr = @RemoveRow
    END
    BEGIN
        SET @RowCounter = @RowCounter + 1
    END
END

错误

Msg 512, Level 16, State 1, Line 212
Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

Answer 1

如果我没听错，您可以在一条语句中删除 "mirror" 条记录，而无需使用额外的计算列：

delete t
from #tbl_LinkedInvoices t
where exists (
    select 1 
    from #tbl_LinkedInvoices t1 
    where 
        t1.AssociatedInvoiceNbr = t.InvoiceNbr
        and t1.InvoiceNbr = t.AssociatedInvoiceNbr
        and t1.AssociatedInvoiceNbr > t.AssociatedInvoiceNbr
)

这将删除镜像记录，同时保留 InvoiceNbr 小于 AssociatedInvoiceNbr 的镜像记录。

Demo on DB Fiddle 与您的示例数据。

delete语句执行后，table的内容为：

InvoiceNbr | AssociatedInvoiceNbr | RowNbr | AssociatedRowNbr
:--------- | :------------------- | -----: | ---------------:
A0001      | A1001                |      1 |                4
A0002      | A2002                |      2 |                5
A0002      | A3002                |      3 |                6

删除重复的行集

Removing Duplicate Sets of Rows

sql

tsql

sql-server

duplicates

sql-delete

数据

Challenge/Goal

脚本

错误