Question

我在mssql（2005）中有一个表，其中有四个日期列和一个ID列。

我想返回所有四列的最小日期和相关的ID。

SELECT TOP 1 min(date1), min(date2), min(date3), min(date4)  FROM datatable
WHERE  date1 > CAST(? AS DATETIME) OR 
     date2 > CAST(? AS DATETIME) OR
     date3 > CAST(? AS DATETIME) OR
     date4 > CAST(? AS DATETIME)

我然后在php中对日期进行排序以给出最小行。我无法解决如何添加返回id的问题。

Answer 1

您可以将列拆分为行，然后使用TOP 1选择最小值（因为这样您还可以找出最少的四列中的哪一列）：

SELECT  t.ID, upvt.Date, upvt.ColumnName
FROM    Datatable AS t
        CROSS APPLY
        (   SELECT  TOP 1 ColumnMame, Date
            FROM    (VALUES 
                        ('Date1', Date1),
                        ('Date2', Date2),
                        ('Date3', Date3),
                        ('Date4', Date4)
                    ) AS d (ColumnName, Date)
            ORDER BY d.Date 
        ) AS upvt

修改

刚看到这是SQL Server 2005，所以你不能使用表值构造函数来取消数据的转移，你需要使用SELECT和UNION ALL

SELECT t.ID, upvt.Date, upvt.ColumnName FROM Datatable AS t CROSS APPLY ( SELECT TOP 1 ColumnMame, Date FROM ( SELECT Columnname = 'Date1', Date = Date1 UNION ALL SELECT Columnname = 'Date2', Date = Date2 UNION ALL SELECT Columnname = 'Date3', Date = Date3 UNION ALL SELECT Columnname = 'Date4', Date = Date4 ) AS d ORDER BY d.Date ) AS upvt;

Answer 2

SELECT id_column, date1
FROM datatable
WHERE (date1 < date2) AND (date1 < date3) AND (date1 < date4)
UNION
SELECT id_column, date2
FROM datatable
WHERE (date2 < date1) AND (date2 < date3) AND (date2 < date4)
UNION
SELECT id_column, date3
FROM datatable
WHERE (date3 < date1) AND (date3 < date2) AND (date3 < date4)
UNION
SELECT id_column, date4
FROM datatable
WHERE (date4 < date1) AND (date4 < date2) AND (date4 < date3)

MSSQL获取id和四个日期的最小（最早）

2 个答案: