查询中的SQL MAX问题

Question

谁能告诉我为什么这不起作用？它给了我所有的访问日期，我只是在寻找最近的访问日期：

SELECT ID , MAX(CAST((CAST(VISITMO  AS nvarchar(2)) + '/' +
                      CAST(VISITDAY AS nvarchar(2)) + '/' +
                      CAST(VISITYR  AS nvarchar(4))) AS date)
                ) AS LastVisitDATE
  FROM [VisitTable] 
  WHERE ID IN (SELECT ID FROM Table2 WHERE other criteria is met)

GROUP BY ID, VISITYR, VISITMO, VISITDAY

由于我遇到的错误，我一直在添加GROUP BY语句

Answer 1

SELECT ID , MAX(CAST((CAST(VISITMO  AS nvarchar(2)) + '/' +
                      CAST(VISITDAY AS nvarchar(2)) + '/' +
                      CAST(VISITYR  AS nvarchar(4))) AS date)
                ) AS LastVisitDATE
  FROM [VisitTable] 
GROUP BY ID