How to display these data

Question

Hello,
I have a table storing data like this:
item_id status date
1 checkin 7/8/2011
1 checkout 7/9/2011
1 checkin 7/8/2012
1 checkout 7/9/2012
how can I display data like this:
item_id checkin checkout
1 7/8/2011 7/9/2011
1 7/8/2012 7/9/2012
please help me!! many thanks!!

Answer 1

Hi,
Welcome to the forum!
Here's one way:
WITH  got_r_num       AS
     SELECT  item_id, status, dt     -- DATE is not a good column name
     ,     ROW_NUMBER () OVER ( PARTITION BY  item_id
                               ,                    status
                         ORDER BY        dt
                       )   AS r_num
     FROM    table_x
SELECT       item_id
,       MIN (CASE WHEN status = 'checkin'  THEN dt END)     AS checkin
,       MIN (CASE WHEN status = 'checkout' THEN dt END)     AS checkout
FROM       got_r_num
GROUP BY  item_id, r_num
ORDER BY  item_id, r_num
;When you have 1 column on multiple rows, and you want to display it as multiple columns on 1 row, that's called a Pivot . Pivotting assumes there is something in the data that pinpoints which row and column of the output will correspond to each data item in the query. The tricky part about this problem is that there is nothing in the table that uniquely identifies the output row. In the example you gave, there are 2 output rows with the same item_id. So we need to generate something (r_num in the example above) that, taken tiogether with item_id, will uniquely identify the output row.
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all tables involved, and also post the results you want from that data.
Explain, using specific examples, how you get those results from that data.
Always say which version of Oracle you're using (e.g., 11.2.0.2.0). The query above works in Oracle 9.1 (and up), but if you're using Oracle 11, you might want to use the SELECT ... PIVOT feature instead of GROUP BY.
See the forum FAQ {message:id=9360002}
You'll get better answers faster if you always supply this information whenever you post a question.
Edited by: Frank Kulash on Feb 13, 2013 11:31 AM
Added explanation