SQL Server - 高级分组

Question

我的表格包含如下所示的采购契约(Contract):

+------+-----------+------------+---------+------------+-----------+
| type | text      | date       | company | supplierID | name      |
+ -----+-----------+------------+---------+------------+-----------+
| 0    | None      | 2004-03-29 | 310     | 227234     | HRC INFRA |
| 0    | None      | 2007-09-30 | 310     | 227234     | HRC INFRA |
| 0    | None      | 2010-11-29 | 310     | 227234     | HRC INFRA |
| 2    | Strategic | 2011-01-01 | 310     | 227234     | HRC INFRA |
| 0    | None      | 2012-04-10 | 310     | 227234     | HRC INFRA |
+------+-----------+------------+---------+------------+-----------+

在此示例中，契约(Contract)的前三行是相同的。所以我只想要第一个。type = 2 的行是与给定供应商的采购契约(Contract)的变更。我也想选择该行。在最后一行，合约变回 0，因此我也想选择该行。

基本上我想选择第一行和契约(Contract)类型发生变化的行。所以结果应该是这样的:

+------+-----------+------------+---------+------------+-----------+
| type | text      | date       | company | supplierID | name      |
+ -----+-----------+------------+---------+------------+-----------+
| 0    | None      | 2004-03-29 | 310     | 227234     | HRC INFRA |
| 2    | Strategic | 2011-01-01 | 310     | 227234     | HRC INFRA |
| 0    | None      | 2012-04-10 | 310     | 227234     | HRC INFRA |
+------+-----------+------------+---------+------------+-----------+

对我如何实现这一目标有什么建议吗？

Answer 1

;WITH cte AS
 (
  SELECT ROW_NUMBER() OVER (ORDER BY date) AS Id,
         type, text, date, company, supplierId, name
  FROM your_table
  )
  SELECT c1.type, c1.text, c1.date, c1.company,
         c1.supplierId, c1.name
  FROM cte c1 LEFT JOIN cte c2 ON c1.id = c2.id + 1
  WHERE c2.text IS NULL OR c1.text != c2.text

演示 SQLFiddle