Question

我有一个存储消息的表像这样： codMsg，message，anotherCod

1, 'hi', 1
2, 'hello', 1
3, 'wasup', 1
4, 'yo', 2
5, 'yeah', 2
6, 'gogogo', 3

我想知道是否有可能选择另一个的前1个

我的期望：

1, 'hi', 1
4, 'yo', 2
6, 'gogogo', 3

我想要整条线，而不仅仅是另一条线的数量，所以group by不应该工作

Answer 1

select mytable.*
from mytable
join (select min(codMsg) as codMsg, anotherCod from mytable group by 2) x    
    on mytable.codMsg = x.codMsg

Answer 2

SQL Server 2005 +，Oracle：

SELECT codMsg, 
       message, 
       anotherCod
FROM
(
    SELECT codMsg, 
           message, 
           anotherCod,  
           RANK() OVER (PARTITION BY anotherCod ORDER BY codMsg ASC) AS Rank
    FROM mytable
) tmp
WHERE Rank = 1

Answer 3

SELECT
  *
FROM
  myTable
WHERE
  codMSG = (SELECT MIN(codMsg) FROM myTable AS lookup WHERE anotherCod = myTable.anotherCod)

选择每行代码的一行

3 个答案: