使用Joins MySQL从表显示特定记录

Question

I have the following table.

   ID SampleID SampleState Date
1   A1   First 1/10/2013
2   A1   Second 1/11/2013
3   A1   Last   1/12/2013
4   A2   First  1/10/2013
5   A2   Closed 1/11/2013
6   A3   First  1/10/2012
7   A3   Second 1/10/2012

I have to pull out the rows using the following rule.

a.) Display the lowest date of each SampleID provided the date is more than 10 days from current day
b.) Display the latest state of each SampleID.
c.) Do not display the SampleID if any of the state of the SampleID is Closed

For example, For this table, the output should be

    SampleID SampleState Date
     A1   Last   1/10/2013
     A3   Second 1/10/2012

My query doesn't display all the results.

SELECT  a.SampleID,a.SampleState,b.date
FROM    ListOfStates 
        INNER JOIN
        (
            SELECT  ID,SampleID, Max(ID) Max_ID, SampleState
            FROM    ListOfStates 
            GROUP   BY SampleID
        ) a 
    on a.Max_ID = ListOfStates.ID
        INNER JOIN
        (
            SELECT  ID,SampleID, Min(ID) min_ID, date
            FROM    ListOfStates 
            GROUP   BY SampleID
        ) b
on b.min_ID = ListOfStates.ID

where              

 b.Date  < DATE_SUB(CURDATE(), INTERVAL 10 DAY)
and a.SampleState !='Closed'

Answer 1

The following takes your conditions and puts them into a single query:

select SampleId,
       min(case when t.Date < DATE_SUB(CURDATE(), INTERVAL 10 DAY) then date end) as MinDate,
       max(case when t.date = tsum.maxDate then state end) as MostRecentState
from t join
     (select SampleId, max(date) as maxDate
      from t
      group by SampleId
     ) tsum
     on t.SampleId = tsum.SampleId
group by SampleId
having max(case when state = 'Closed' then 1 else 0 end) = 0 and
       min(date) < DATE_SUB(CURDATE(), INTERVAL 10 DAY)

I think the key is the conditional aggregations. You can aggregate things using the case statement in the select clause, rather than filtering using where clause (or having clause).