Question

我有示例数据See the SQL Fiddle。我想从上载日期列中找到值列中的最小值和最低值的日期。我尝试了以下查询，但它没有正常工作并显示所有值。

SELECT
    username,
    MIN(Value1) AS MinValue1,
    CASE 
        WHEN value1 = MIN(value1) THEN uploaded_date
    END
    AS MinDate
FROM
    test

GROUP BY
    username

Answer 1

您可以使用RANK窗口函数查找每个用户名的最小值：

SELECT username, value1, uploaded_date
FROM   (SELECT username, value1, uploaded_date,
               RANK() OVER (PARTITION BY username ORDER BY value1 ASC) AS rk
        FROM   test) t
WHERE  rk = 1

<强> SQLFIddle

Answer 2

SELECT test. username,value1,MIN(uploaded_date  )FROM
(Select MIN(value1) MinValue1,username from test group by username ) A
INNER JOIN
test 
ON A.MinValue1 = test.Value1
AND A.username = test.username
GROUP BY
test. username,value1

您的查询无效，因为您使用的是选择列表中的列，因此Group by子句会将所有不同的值分组到每一行

Answer 3

我希望这会对你有所帮助

  ;with CTE as(
    SELECT username,
      MIN(Value1) AS MinValue1
  FROM
      test
  GROUP BY 
    username
  )

  select c.username,MinValue1,dt.uploaded_date from CTE c
  cross apply(select top 1 uploaded_date from test where value1=c.MinValue1 and username=c.username order by uploaded_date desc) dt

Answer 4

select Value1, update_date from test order by Value1 limit 1

如何查找最低值和相应日期SQL-Server 2014

4 个答案: