Question

 select s.s_nric as NRIC
      , s.s_name as NAME
      , status.st_status
      , DATE_FORMAT(status.st_fromdate,'%d-%m-%Y') as from_date
      , DATE_FORMAT(status.ST_ON,'%d-%m-%Y') as ST_ON

 FROM si_student_data AS s
   LEFT JOIN si_student_status As st
     ON st.st_nric=s.s_nric
   INNER JOIN
     ( SELECT t.st_nric
            , t.st_fromdate
            , t.st_status
            , MAX(t.st_todate) as ST_ON
       FROM si_student_status t
       GROUP BY t.st_nric
     ) AS status
     ON (  s.s_nric=status.st_nric
       AND status.ST_ON=st.st_todate )
   LEFT JOIN si_student_changes as s1
     ON s1.ch_nric = s.s_nric

   where 1=1
     AND s1.ch_class='2S1'
     AND s1.ch_year='2011'

   GROUP BY s.s_nric

   ORDER BY s1.ch_class
          , s.s_gender
          , s.s_name asc

当我使用此查询时，我可以使用相应的nric编号获得最大日期值。但我无法获得与日期相关的其他值。它只选取了具有不同行值的最大日期。我想要相关的值（状态）到日期我的样本表：第一个表：si_student_data

s_nric           s_name
1                Suba
2                Felix
3                welcome

第二张tabe：si_student_changes

ch_nric            ch_year          ch_class
1                  2011              2S1
2                  2011              2S1
3                 2011               2S1
4                 2010               1A1
5                 2011               2T3
1                 2010               1A1

第三张表：si_student_status

st_nric             st_status           st_fromdate              st_todate
  1                      Active             10-10-2011            10-11-2011
  1                      Inactive            11-11-2011            12-12-2011
  1                      PRO                 13-12-2011            22-12-2011
  2                     LWR                  10-10-2011            10-11-2011
  2                     Inactive              11-11-2011            12-12-2011
  2                      ATTR                 13-12-2011           20-12-2011
3                       Active              04-01-2011       10-05-2011

3 Inactive 11-05-2011 12-08-2011 3 PRO 13-08-2011 20-10-2011

我期待的输出

 s_nric      s_name     st_status  st_fromdate         st_todate
1          Suba       PRO       13-12-2011           22-12-2011
2          Felix      ATTR     13-12-2011           20-12-2011
3          welcome    PRO      13-08-2011           20-10-2011

请解释如何获得最大日期值记录。我想要最大日期和相同的行值..

Answer 1

只需在表格st中添加您想要的字段即可。并且不要在SELECT列表中使用status.*：

select s.s_nric as NRIC
     , s.s_name as NAME

     , st.st_status
     , DATE_FORMAT(st.st_fromdate,'%d-%m-%Y') as from_date
     , DATE_FORMAT(st.st_todate,'%d-%m-%Y') as ST_ON

因此，整个查询可以写成：

 SELECT s.s_nric AS NRIC
      , s.s_name AS NAME 
      , st.st_status
      , DATE_FORMAT(st.st_fromdate,'%d-%m-%Y') AS from_date
      , DATE_FORMAT(st.st_todate,'%d-%m-%Y') AS ST_ON

 FROM si_student_data AS s
   LEFT JOIN si_student_status AS st
     ON st.st_nric = s.s_nric
   INNER JOIN
     ( SELECT t.st_nric
            , MAX(t.st_todate) AS ST_ON
       FROM si_student_status t
       GROUP BY t.st_nric
     ) AS status
     ON (  s.s_nric = status.st_nric
       AND status.ST_ON = st.st_todate )
   LEFT JOIN si_student_changes as s1
     ON s1.ch_nric = s.s_nric

   WHERE 1=1
     AND s1.ch_class='2S1'
     AND s1.ch_year='2011'

   GROUP BY s.s_nric

   ORDER BY s1.ch_class
          , s.s_gender
          , s.s_name asc

Answer 2

SELECT s.*,p.name, FROM `status` as s 
left join profile as p ( s.id = p.id)
WHERE s.date= ( select MAX(s.date) from status)

获取最新日期行值

2 个答案: