Converting Rows to Columns

Question

I have a Customer TABLE which has 3 COLUMNS
Custid,Did,Dname
1,10,AA
1,20,BB
1,20,BB
2,10,CC
3,10,DD
3,20,FF
4,10,EE
5,20,CC
5,20,CC
WHEN i RUN a SELECT DISTINCT CustId,Did,Dname FROM THE TABLE..I see 1 OR 2( MAX) records for any customer.
Custid,Did,Dname
1,10,AA
1,20,BB
2,10,CC
3,10,DD
3,20,FF
4,10,EE
5,20,CC
THE O/p shd be ..FOR Custid =1 i see 2 record..so it will have values in Did2,Dname2 columns also.
For Custid=2..I only have one record..So the Did2,Dname2 columns will be null
O/P
CustId,Did1,Dname1,Did2,Dname2
1,10,AA,20,BB
2,10,CC,NULL,NULL
3,10,CC,20,FF
4,10,EE,NULL,NULL
5,20,CC,NULL,NULL
Please help in writing the query

Answer 1

This may be a bit overdone, but here's what I came up with:
SELECT t7.Custid,
t7.DID,
          t7.Dname,
          (SELECT DISTINCT tc.DID FROM temptest tc WHERE tc.Custid = t7.Custid AND tc.DID > t7.DID) DID2,
          (SELECT DISTINCT tc.Dname FROM temptest tc WHERE tc.Custid = t7.Custid AND tc.DID > t7.DID) Dname2
FROM temptest t7
WHERE t7.Custid IN (SELECT DISTINCT t3.Custid
FROM temptest t3
WHERE t3.Custid IN (SELECT t8.Custid FROM temptest t8 INNER JOIN temptest t9 ON (t8.Custid = t9.Custid AND t8.DID = t9.DID AND t8.Dname = t9.Dname)
WHERE t8.DID > (SELECT MIN(ta.DID) FROM temptest ta WHERE ta.Custid = t8.Custid)
GROUP BY t8.Custid, t8.DID, t8.Dname))
AND t7.DID IN (SELECT min(tb.DID) FROM temptest tb WHERE tb.Custid IN (SELECT DISTINCT t3.Custid
FROM temptest t3
WHERE t3.Custid IN (SELECT t8.Custid FROM temptest t8 INNER JOIN temptest t9 ON (t8.Custid = t9.Custid AND t8.DID = t9.DID AND t8.Dname = t9.Dname)
WHERE t8.DID > (SELECT MIN(ta.DID) FROM temptest ta WHERE ta.Custid = t8.Custid)
GROUP BY t8.Custid, t8.DID, t8.Dname)))
UNION
SELECT t4.Custid,
t4.DID,
          t4.Dname,
          NULL DID2,
          NULL Dname2
FROM temptest t4 INNER JOIN temptest t5 ON (t4.Custid = t5.Custid AND t4.DID = t5.DID AND t4.Dname = t5.Dname)
WHERE t4.DID <= (SELECT MIN(t6.DID) FROM temptest t6 WHERE t6.Custid = t4.Custid)
GROUP BY t4.Custid, t4.DID, t4.Dname
HAVING count(t4.Custid) > 1
UNION
SELECT t1.Custid,
t1.DID,
          t1.Dname,
          NULL DID2,
          NULL Dname2
FROM temptest t1
WHERE t1.Custid IN (SELECT t2.Custid FROM temptest t2 GROUP BY t2.Custid HAVING count(*) = 1)
Sorry, the formatting is lost.
I basically broke out the different type of data you would find in your sample dataset (hopefully, the real data is represented similarly) and queried it separately.