Question

我有下表：

Record   ID   Status     Date          Timestamp
----------------------------------------------------------
1        1    waiting    2010-02-02    2010-02-02 12:00:00
2        1    finished   2010-02-02    2010-02-02 12:30:00
3        2    waiting    2009-02-02    2009-02-02 12:00:00

我想获取日期在2010-01-01和2010-03-03之间的记录。（这应该给我记录1和2）

此外，我想为每个ID仅获取最新的（具有最新时间戳）。（这应该只给我记录2）。

我不确定如何构建查询。我已设法构建以下查询：

SELECT   `Record` `ID`, MAX(  `Timestamp` ) 
FROM     `myTable` 
WHERE    `Date` 
BETWEEN  '2010-01-01'
AND      '2011-03-03'
GROUP BY `ID`

上述查询的问题在于，由于某种原因，它给出了以下结果：

Record   ID   Timestamp
---------------------------------
1        1    2010-02-02 12:30:00

这是正确的，除了Record字段的值应为2而不是1.

Answer 1

SELECT t1.* 
FROM `myTable` t1
INNER JOIN
(
SELECT MAX(`Timestamp`) as Timestamp
FROM     `myTable`
WHERE    `Date` 
BETWEEN  '2010-01-01'
AND      '2011-03-03'
GROUP BY `ID` 
) t2
ON t1.Timestamp = t2.Timestamp

Answer 2

尝试以下查询

SELECT   `Record` `ID`,Timestamp
FROM     `myTable` 
WHERE    `Date` 
BETWEEN  '2010-01-01'
AND      '2011-03-03'
Order by `Timestamp` desc
limit 1

具有日期范围的mySQL查询，并仅为每个ID选择最新记录

2 个答案: