Question

我问了这个问题并得到了一个很好的答案：How to assign date value to all returned mysql queries但现在我需要在MS SQL（SQL Server 2005）中做同样的事情。警告是我有一个案例陈述，似乎是破坏事情。我有两个问题：

select * from (select row_number()
  over (order by a.device ASC)
  AS rownum, a.device, staff, requestDate, m.maxDate, attribute = 
                 REPLACE((SELECT attribute AS [data()]
                 FROM deviceList
                 WHERE device = a.device
                 ORDER BY device FOR xml PATH('')), ' ',  ' ')
  FROM deviceList a
  INNER JOIN (SELECT device, MAX(requestDate) AS maxDate
                 FROM ASSIGNMENT GROUP BY device) m on m.device = a.device
  RIGHT JOIN Assignment
      ON (Assignment.device=a.device)
  GROUP BY a.device, staff, maxDate, requestDate, contract)
  AS B WHERE B.rownum > 0;





select * from (select row_number()
  over (order by a.device ASC)
  AS rownum, a.device, staff, requestDate, CONVERT(
    varchar, dateadd(year,
    (CASE
        WHEN contract = '10' THEN 1
        WHEN contract = '20' THEN 2
        WHEN contract = '30' THEN 3
        ELSE 3
        END), m.maxDate) 107) as myEndDate, attribute = 
                 REPLACE((SELECT attribute AS [data()]
                 FROM deviceList
                 WHERE device = a.device
                 ORDER BY device FOR xml PATH('')), ' ',  ' ')
  FROM deviceList a
  INNER JOIN (SELECT device, MAX(requestDate) AS maxDate
                 FROM ASSIGNMENT GROUP BY device) m on m.device = a.device
  RIGHT JOIN Assignment
      ON (Assignment.device=a.device)
  GROUP BY a.device, staff, myEndDate, requestDate, contract)
  AS B WHERE B.rownum > 0;

第一个语句非常有用，例如条目（具有相同“设备”标签的条目）具有正确的endDate。但是，当我尝试根据case语句递增日期时，事情就会出错。日期递增但不相同。为什么案件陈述会破坏这种性质？

更新：如果我有一个设备的两个日期值：

2/1/2010
1/1/2010

合同= 10

查询后

各自的日期是：

2/1/2011
2/1/2012

Answer 1

您必须使用CASE子句中的整个GROUP BY语句。 SQL Server不一定在执行SELECT之前处理GROUP BY元素，因此不能使用在那里定义的别名。（Longer explanation here）。

SELECT * FROM (SELECT ROW_NUMBER()
  OVER (ORDER BY a.device ASC)
  AS rownum, a.device, staff, requestDate, CONVERT(
    varchar, dateadd(year,
    (CASE
        WHEN contract = '10' THEN 1
        WHEN contract = '20' THEN 2
        WHEN contract = '30' THEN 3
        ELSE 3
        END), m.maxDate) 107) as myEndDate, attribute = 
                 REPLACE((SELECT attribute AS [data()]
                 FROM deviceList
                 WHERE device = a.device
                 ORDER BY device FOR xml PATH('')), ' ',  ' ')
  FROM deviceList a
  INNER JOIN (SELECT device, MAX(requestDate) AS maxDate
                 FROM ASSIGNMENT GROUP BY device) m on m.device = a.device
  RIGHT JOIN Assignment
      ON (Assignment.device=a.device)
  GROUP BY a.device, staff, CONVERT(
    varchar, dateadd(year,
    (CASE
        WHEN contract = '10' THEN 1
        WHEN contract = '20' THEN 2
        WHEN contract = '30' THEN 3
        ELSE 3
        END), m.maxDate) 107), requestDate, contract)
  AS B WHERE B.rownum > 0;

如何获得所有类似条目MySQL的maxdate

1 个答案: