Question

我的桌子上有这样的记录：

+------+------+
| ID   | name |
+------+------+
|    1 | A    |
|    2 | B    |
|    3 | C    |
|    4 | A    |
|    5 | B    |
|    6 | A    |
|    7 | A    |
|    8 | A    |
+------+------+

我需要在上次从不同的值更新后获取A的值，例如此处它将是ID为6的行。

Answer 1

尝试此查询（MySQL语法）：

select min(ID) 
from records 
where name = 'A' 
and ID >= 
(
  select max(ID) 
  from records 
  where name <> 'A'
);

插图：

select * from records;
+------+------+
| ID   | name |
+------+------+
|    1 | A    |
|    2 | B    |
|    3 | C    |
|    4 | A    |
|    5 | B    |
|    6 | A    |
|    7 | A    |
|    8 | A    |
+------+------+

- 运行查询：

+---------+
| min(ID) |
+---------+
|       6 |
+---------+

Answer 2

使用Lag function ...

SELECT Max([ID]) 
FROM   (SELECT [name], [ID], 
               Lag([name]) OVER (ORDER BY [ID]) AS PrvVal 
        FROM   tablename) tbl 
WHERE  [name] = 'A' 
       AND prvval <> 'A'

在线演示：http://www.sqlfiddle.com/#!18/a55eb/2/0

如果你想获得整行，你可以这样做......

SELECT   Top 1 *
FROM     (SELECT [name], [ID], 
               Lag([name]) OVER (ORDER BY [ID]) AS PrvVal 
          FROM   tablename) tbl 
WHERE    [name] = 'A' AND prvval <> 'A'   
ORDER BY [ID] DESC

在线演示：http://www.sqlfiddle.com/#!18/a55eb/22/0

Answer 3

下面的ANSI SQL在前一个id上使用自联接。

where子句获取的名称与之前的名称不同。

ID+1

它应该适用于大多数RDBMS，包括MS Sql Server。

请注意，delete [] a;假设ID之间没有间隙。

获取最新更新的名称

3 个答案: