Question

I would like to know if there is an easy way to join pairs of records in a single table to form one table. For example:

ID, TYPE, TIME

1, A, 01:00:00

2, B, 02:00:00

3, A, 03:00:00

4, B, 04:00:00

5, A, 05:00:00

what i would like to retreive is a single table listing the pairs (A/B) like so.

ID, TYPE, TIME, ID, TYPE, TIME

1, A, 01:00:00, 2, B, 02:00:00

3, A, 03:00:00, 4, B, 04:00:00

5, A, 05:00:00,NULL,NULL,NULL

The B record should be the next one after A, and if there is no B then just return NULL. The table shall be sorted chronigically.

TIA

Answer 1

Thanks ajreal, it helped me find the answer:

SELECT T.ID,T.Type,T.Time,T2.ID,T2.Type,T2.Time FROM Table T LEFT JOIN Table T2 
ON (T.Type = 'A' AND T2.Type = 'B' AND T.Time < T2.Time) 
WHERE T2.ID IS NOT NULL
GROUP BY T.ID