I would like to transfer some existing data into new data table.
I have table with substitutions:
- ID
- currentItemId
- formerItemId
- contentId
For the same content there is possibility I have multiple entries for combinations currentItemId and formerItemId.
Let me show how it is now:
ID_T1 currentItemId formerItemId contentId
1 100 200 300
2 100 200 301
3 100 200 302
4 105 201 303
5 105 201 304
6 110 205 320
7 111 206 321
8 120 204 322
9 130 208 323
10 130 208 324
Now, I would like to select TOP ID for each combination formerItemId and currentItemId:
ID ID_T1 contentId
1 1 300
2 1 301
3 1 302
4 4 303
5 4 304
6 6 320
7 7 321
8 8 322
9 9 323
10 9 324
Both tables also contains timestamp and some other data - I haven't included that in order example to be more understandable.
I tried self join (no success), nested select (gives me right value for the original combination, but it doesn't repeat, it gives me NULL on ID for other records), but nothing seems to work. Tried something like:
SELECT di1.ID,
(SELECT TOP(1) di1.ID
FROM TABLE
WHERE
di1.currentItemtId = di2.currentItemtId AND di1.formerItemId = di1.formerItemId
) AS repeat
,di2.deleteItemId
,di1.currentitemtId
,di1.formerItemId
,di1.contentId
FROM Table di1
LEFT JOIN
Table di2 ON di1.ID = di2.ID
But this way ID doesn't repeat - I get same values for ID as in ordinary select.
I am using SQL server 2008.
Any help would be greatly appreciated.