如果数据不同，则为备用编号行

问题描述

当前数据：

|LotNumber |ItemNumber |ItemName
|76        |1          |WidgetRight
|76        |1          |WidgetLeft
|76        |2          |WidgetRight
|76        |2          |WidgetLeft
|76        |7          |WidgetRight
|76        |7          |WidgetLeft
|76        |9          |WidgetRight
|76        |10         |WidgetRight
|76        |10         |WidgetLeft
|80        |3          |WidgetRight
|80        |3          |WidgetLeft
|80        |7          |WidgetRight
|80        |7          |WidgetLeft
|80        |11         |WidgetRight
|80        |31         |WidgetRight

每次ItemNumber更改时，需要添加一列，该列在1和2之间交替显示

|LotNumber |ItemNumber |ItemName       |NewField
|76        |1          |WidgetRight    |1
|76        |1          |WidgetLeft     |1
|76        |2          |WidgetRight    |2
|76        |2          |WidgetLeft     |2
|76        |7          |WidgetRight    |1
|76        |7          |WidgetLeft     |1
|76        |9          |WidgetRight    |2
|76        |10         |WidgetRight    |1
|76        |10         |WidgetLeft     |1
|80        |3          |WidgetRight    |2
|80        |3          |WidgetLeft     |2
|80        |7          |WidgetRight    |1
|80        |7          |WidgetLeft     |1
|80        |11         |WidgetRight    |2
|80        |31         |WidgetRight    |1

当前代码不起作用...

DECLARE @LastLine Varchar(1)

SELECT ItemNumber,ItemName,CASE WHEN ItemNumber <> LAG (ItemNumber,1,0) OVER (PARTITION BY LotNumber ORDER BY LotNumber,ItemNumber )
THEN
    CASE WHEN @LastLine = '1'
    THEN  '2'
    ELSE  '1'
    END 
END AS LastLine

谢谢您的帮助。

解决方法

您可以只使用dense_rank()和算术：

select t.*,1 + (dense_rank() over(order by lotnumber,itemnumber) + 1) % 2 as newfield
from mytable t

Demo on DB Fiddle