SQL UPDATE 和 CASE 语句不起作用

Question

我在 MS SQL 服务器中有以下 table“销售”，其中 [FieldX] 未正确更新：

(..[我的评论] 当然不是 table 中的实际列)

最后 3 行应为 = 3 的原因是因为我正在使用以下规则更新字段：

with cte_previous_rows AS (
SELECT Staff_Id, LAG(FieldX) OVER (partition by Staff_Id ORDER by [date]) as Prev_Row
FROM Sales )

UPDATE Sales
SET FieldX = (CASE WHEN Staff_id_sales < 1500 AND ClosedSale = 0 THEN 0
           WHEN Staff_id_sales = 1500 and CosedSale = 0 THEN 5
           WHEN Staff_id_sales > 3000 and c.Prev_Row <> 2 and c.Prev_Row = 1 OR c.Prev_Row = 0 THEN 2
           WHEN Staff_id_sales > 3000 and c.Prev_Row = 2 or c.Prev_Row = 3 THEN 3 END) 
FROM Sales as Sales
JOIN cte_previous_rows as c
 on sales.staff_id = c.staff_id

这里的想法是确定上一行在 [FieldX] 中作为值保存的内容。通过“上一行”，我指的是具有相同 staff_id 和最接近的前一个 [date]

的其他行

最后两个 WHEN 语句没有按预期工作，因为我在 Sales table 中显示了输出。

正确的输出应该是这样的：

我做错了什么？如何修复？谢谢。

Answer 1

请检查下一个查询：

WITH cte_previous_rows AS (
    SELECT Date, Staff_Id, LAG(FieldX) OVER (partition by Staff_Id ORDER by [date]) as Prev_Row
FROM Sales 
) UPDATE Sales
SET FieldX = (CASE 
    WHEN Staff_id_sales < 1500 AND ClosedSale = 0 THEN 0
    WHEN Staff_id_sales = 1500 and ClosedSale = 0 THEN 5
    WHEN Staff_id_sales > 3000 and (c.Prev_Row = 1 OR c.Prev_Row = 0) THEN 2
    WHEN Staff_id_sales > 3000 and (c.Prev_Row = 2 or c.Prev_Row = 3) THEN 3 
    ELSE FieldX
END) 
FROM Sales
JOIN cte_previous_rows as c ON Sales.staff_id = c.staff_id AND Sales.Date = c.Date;

结果：

+============+==========+================+============+========+
| Date       | Staff_Id | Staff_id_sales | ClosedSale | FieldX |
+============+==========+================+============+========+
| 2000-01-01 | 1        | 500            | 0          | 0      |
+------------+----------+----------------+------------+--------+
| 2001-01-01 | 2        | 200            | 0          | 0      |
+------------+----------+----------------+------------+--------+
| 2001-02-26 | 3        | 500            | 0          | 0      |
+------------+----------+----------------+------------+--------+
| 2001-01-25 | 4        | 1500           | 0          | 5      |
+------------+----------+----------------+------------+--------+
| 2001-03-25 | 4        | 1500           | 0          | 5      |
+------------+----------+----------------+------------+--------+
| 2001-03-25 | 5        | 2500           | 0          | 1      |
+------------+----------+----------------+------------+--------+
| 2001-04-25 | 5        | 3000           | 0          | 1      |
+------------+----------+----------------+------------+--------+
| 2001-05-25 | 5        | 3500           | 0          | 2      |
+------------+----------+----------------+------------+--------+
| 2001-05-26 | 5        | 4000           | 0          | 3      |
+------------+----------+----------------+------------+--------+
| 2001-05-27 | 5        | 5000           | 0          | 3      |
+------------+----------+----------------+------------+--------+
| 2001-05-28 | 5        | 7500           | 0          | 3      |
+------------+----------+----------------+------------+--------+

SQL UPDATE 和 CASE 语句不起作用

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