Question

我有一个表名batch_log，其结构如下

batch_id    run_count   start_date  end_date
1           4           03/12/2014  03/12/2014
1           3           02/12/2014  02/12/2014
1           2           01/12/2014  01/12/2014
1           1           30/11/2014  30/11/2014
2           5           03/12/2014  03/12/2014
2           4           02/12/2014  02/12/2014
2           3           01/12/2014  01/12/2014
2           2           30/11/2014  30/11/2014
2           1           29/11/2014  29/11/2014
3           3           02/12/2014  02/12/2014
3           2           01/12/2014  01/12/2014
3           1           30/11/2014  30/11/2014

我需要使用max run_count获取所有batch_id的行。查询结果应为：

batch_id    run_count   start_date  end_date
1           4           03/12/2014  03/12/2014
2           5           03/12/2014  03/12/2014
3           3           02/12/2014  02/12/2014

我尝试了很多选项，group by batch_id和run_count但无法获得正确的结果

select a.* from batch_log a,batch_log b 
where a.batch_id =b.batch_id
and a.run_count=b.run_count
and a.run_count in (select max(run_count) from batch_log
group by batch_id ) order by a.batch_id

请求帮助

Answer 1

select *
from(
select a.*, max(run_count) over (partition by batch_id) max_run_count
from batch_log a)
where run_count=max_run_count;

Answer 2

这也应该有效：

SELECT * FROM batch_log b1
WHERE b1.run_count = (SELECT max(b2.run_count) 
                      FROM batch_log b2 
                      WHERE b2.batch_id = b1.batch_id 
                      GROUP BY b2.batch_id)

Answer 3

您可以通过此查询执行此操作：

select * 
from batch_log a
inner join (
            select b.batch_id , max(run_count) as run_count 
            from batch_log b 
            group by b.batch_id 
            ) c on a.batch_id = c.batch_id and a.run_count = c.run_count

希望有所帮助

Answer 4

Arion给出的答案看起来很完美。您可以按照以下修改，以达到您的确切要求

SELECT batch_id,run_count,start_date,end_date
FROM
( 
    SELECT
        ROW_NUMBER() OVER(PARTITION BY batch_id ORDER BY run_count DESC) AS RowNbr,
        batch_log.*
    FROM
        batch_log
) as batch
WHERE 
    batch.RowNbr=1

查询从表中获取最大记录

4 个答案: