另一种使用CASE WHEN的方法

SELECT CASE true 
       WHEN max(row1) >= max(row2) THEN CASE true WHEN max(row1) >= max(row3) THEN max(row1) ELSE max(row3) end ELSE
       CASE true WHEN max(row2) >= max(row3) THEN max(row2) ELSE max(row3) END END
FROM yourTable

以下两个示例中的任何一个都可以工作:

SELECT  MAX(date_columns) AS max_date
FROM    ( (SELECT   date1 AS date_columns
           FROM     data_table         )
          UNION
          ( SELECT  date2 AS date_columns
            FROM    data_table
          )
          UNION
          ( SELECT  date3 AS date_columns
            FROM    data_table
          )
        ) AS date_query

第二个是对拉塞夫克的答案的补充。

SELECT  MAX(MostRecentDate)
FROM    ( SELECT    CASE WHEN date1 >= date2
                              AND date1 >= date3 THEN date1
                         WHEN date2 >= date1
                              AND date2 >= date3 THEN date2
                         WHEN date3 >= date1
                              AND date3 >= date2 THEN date3
                         ELSE date1
                    END AS MostRecentDate
          FROM      data_table
        ) AS date_query 

For T-SQL (MSSQL 2008+)

SELECT
  (SELECT
     MAX(MyMaxName) 
   FROM ( VALUES 
            (MAX(Field1)), 
            (MAX(Field2)) 
        ) MyAlias(MyMaxName)
  ) 
FROM MyTable1

基于http://www.experts-exchange.com/Microsoft/Development/MS-SQL-Server/Q_24204894.html的ScottPletcher的解决方案 我已经创建了一组函数(例如GetMaxOfDates3, GetMaxOfDates13)，以使用UNION ALL找到最多13个日期值。 参见T-SQL函数从同一行获取最大值 然而，在编写这些函数时，我还没有考虑过UNPIVOT解决方案

CREATE FUNCTION GetMaxOfDates13 (
@value01 DateTime = NULL,  
@value02 DateTime = NULL,
@value03 DateTime = NULL,
@value04 DateTime = NULL,
@value05 DateTime = NULL,
@value06 DateTime = NULL,
@value07 DateTime = NULL,
@value08 DateTime = NULL,
@value09 DateTime = NULL,
@value10 DateTime = NULL,
@value11 DateTime = NULL,
@value12 DateTime = NULL,
@value13 DateTime = NULL
)
RETURNS DateTime
AS
BEGIN
RETURN (
SELECT TOP 1 value
FROM (
SELECT @value01 AS value UNION ALL
SELECT @value02 UNION ALL
SELECT @value03 UNION ALL
SELECT @value04 UNION ALL
SELECT @value05 UNION ALL
SELECT @value06 UNION ALL
SELECT @value07 UNION ALL
SELECT @value08 UNION ALL
SELECT @value09 UNION ALL
SELECT @value10 UNION ALL
SELECT @value11 UNION ALL
SELECT @value12 UNION ALL
SELECT @value13
) AS [values]
ORDER BY value DESC    
)
END –FUNCTION
GO
CREATE FUNCTION GetMaxOfDates3 (
@value01 DateTime = NULL,  
@value02 DateTime = NULL,
@value03 DateTime = NULL
)
RETURNS DateTime
AS
BEGIN
RETURN dbo.GetMaxOfDates13(@value01,@value02,@value03,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL)
END –FUNCTION

下面是使用T-SQL和SQL Server实现Max功能的另一个很好的解决方案

SELECT [Other Fields],
  (SELECT Max(v) 
   FROM (VALUES (date1), (date2), (date3),...) AS value(v)) as [MaxDate]
FROM [YourTableName]

Values是表值构造函数。

"指定要构造到表中的一组行值表达式。Transact-SQL表值构造函数允许在单个DML语句中指定多行数据。表值构造函数可以指定为INSERT…VALUES语句，或者作为MERGE语句的USING子句或FROM子句中的派生表。

请尝试使用UNPIVOT:

SELECT MAX(MaxDt) MaxDt
   FROM tbl 
UNPIVOT
   (MaxDt FOR E IN 
      (Date1, Date2, Date3)
)AS unpvt;