来自单个表的链接记录，两个表在PHP mysql中

Question

I have two columns ie:

   caseSno                 newCaseSno
   7592                     7593
   7591                     7592
   2935                     7591
   7092                     7572

In the above table caseSno and new CaseSno are two columns where in caseSno is the original case number while after case has been transferred to someone else newCaseSno keep the new number, now I want to find all the associated cases herein this table. ie in the first row caseSno 7593 should be splayed in my report 4 times as it is associated with 7593,7592,7591 and 2935. In simple words I need something like Friends of friend mechanism

Please help me, how to find out all the record associated to each column in other.

Simple and fast executable query will be appreciated.

Answer 1

One idea would be to define three tables:

CaseTbl         Person             CasePersonHistory
------------    --------------     ------------------
case_id (PK)    person_id (PK)     case_id   (PK)
case_name       etc etc...         person_id (PK)
case_descr                         seq_num   (PK)
etc etc...                         etc etc...

EDIT: Can't use case for table name... choose something else instead

The CaseTbl always has one id... it's unique description. Same for Person . CasePersonHistory supplies a many-to-many relationship between cases and people with a sequence number, where the highest seq_num would be the person who currently owns the case, and all lower seq_num s being people who previously owned the case.

So for example, if

fred's person_id  = 54
mikes's person_id = 55
jane's person_id  = 56

If the case_id is 1 , And Fred originally had the case, then gave it to Mike, who then gave it to Jane then CasePersonHistory would look like...

CasePersonHistory
------------------
case_id      person_id     seq_num
-----------------------------------
1            54            1
1            55            2
1            56            3

Now you can find out who the current owner or owners of the case are by selecting from the table based on the case_id and finding the max of the sequence number:

SELECT MAX(seq_num) FROM CasePersonHistory WHERE case_id = 1;

or to get the person who currently owns the case...

SELECT person_id FROM CasePersonHistory WHERE case_id = 1 order by seq_no DESC LIMIT 1

Hope that helps :)