Question

我有一个表，它使用ID和GUID进行版本控制。 ID增加，但GUID是静态的，允许版本控制。

例如：

ID     GUID        Data
01     ASD         Something
02     ASD         Something Changed
03     ASD         Something Changed Again
04     DSA         Something Else
05     DSA         Something Else Changed

所以问题是，你如何得到最新的数据，所以最终得到：

03     ASD         Something Changed Again
05     DSA         Something Else Changed

Answer 1

试试这个：

SELECT t1.id, t1.guid, t1.Data
FROM   table t1
JOIN ( SELECT MAX(id) AS id, guid
       FROM table GROUP BY guid ) t2
       ON t1.id = t2.id AND t1.guid = t2.guid

Answer 2

您也可以尝试

DECLARE @Table TABLE(
        ID INT,
        GUID VARCHAR(10),
        Data VARCHAR(100)
)

INSERT INTO @Table SELECT 01,'ASD','Something'
INSERT INTO @Table SELECT 02,'ASD','Something Changed'
INSERT INTO @Table SELECT 03,'ASD','Something Changed Again'
INSERT INTO @Table SELECT 04,'DSA','Something Else'
INSERT INTO @Table SELECT 05,'DSA','Something Else Changed'


SELECT  *
FROM    @Table t
WHERE   t.ID = ( SELECT MAX(ID) ID 
              FROM @Table 
              WHERE GUID = t.GUID GROUP BY GUID)

您应该尝试对两种解决方案（例如@Rubens Farias提供的解决方案）进行性能检查，并根据您拥有的索引查看最适合您的解决方案。

获取最新的版本控制数据

2 个答案: