Cross tab using sql

Question

Hi,
I am using oracle 11g version.
I have a reporting requirement where in I have to produce a cross tab as explained below. Please help me in writing an SQL query to achieve this. Many thanks.
Sample data:
Customer             product type
AAA                           DVD
AAA                           Tape
BBB                           Tape
CCC                                 DVD
CCC                           Bluray
DDD                           DVD
DDD                           Tape
DDD                           Bluray
Logic
     AAA                                              BBB                         CCC                         DDD          
     DVD     Tape     Bluray                    DVD     Tape     Bluray               DVD     Tape     Bluray               DVD     Tape     Bluray
DVD          1                    DVD                         DVD               1          DVD          1     
Tape     1                         Tape          1               Tape                         Tape     1          1
Bluray                              Bluray                         Bluray     1                    Bluray          1                                                                                                    Final Output
No. of customers who purchased the products across all product types
     DVD     Tape     Bluray               
DVD          2     1               
Tape     2     1     1               
Bluray     1     1                    
Scripts:
create table cust_product(customer varchar2(5), product_type varchar2(10));
insert into cust_product values('AAA','DVD');
insert into cust_product values('AAA','Tape');
insert into cust_product values('BBB','Tape');
insert into cust_product values('CCC','DVD');
insert into cust_product values('CCC','Bluray');
insert into cust_product values('DDD','DVD');
insert into cust_product values('DDD','Tape');
insert into cust_product values('DDD','Bluray');

Answer 1

Hi,
858747 wrote:
... Sample data:
Customer             product type
AAA                           DVD
AAA                           Tape
BBB                           Tape
CCC                                 DVD
CCC                           Bluray
DDD                           DVD
DDD                           Tape
DDD                           Bluray...
Final Output
No. of customers who purchased the products across all product types
`     DVD     Tape     Bluray               
DVD          2     1               
Tape     2     1     1               
Bluray     1     1                    
Sorry, I don't follow the logic. Try explaining in words, with specific examples.
Didn't 2 distinct customers, 'CCC' and 'DDD', buy both 'DVD' and 'Bluray'? Why aren't the results
`     DVD     Tape     Bluray               
DVD          2     2
Tape     2     1     1               
Bluray     2     1                    with 2's in the corners?
Assuming that was just mistake, you can do something like this:
WITH     got_pairs     AS
     SELECT       a.product_type               AS product_a
     ,       NVL (b.product_type, a.product_type)     AS product_b
     FROM            cust_product     a
     LEFT OUTER JOIN     cust_product     b  ON  a.customer     = b.customer
                            AND     a.product_type != b.product_type
SELECT       *
FROM       got_pairs
PIVOT       (     COUNT (*)
       FOR     product_b
       IN     ( 'DVD'
          , 'Tape'
          , 'Blueray'
ORDER BY  CASE  product_a
          WHEN  'DVD'     THEN  1
          WHEN  'Tape'     THEN  2
          WHEN  'Bluray'     THEN  3
       END
;This assumes that the combination (customer, product_type) is unique, as it is in your sample data., and that the only product_types are the 3 in your sample data.
if those assumptions are not true, then post some revised sample data and results, that show what you want in those cases.
Sorry, I don't have an Oracle 11 database right now to test this.
I can (and did) test the outer join, that combines a product_type with itself only if it can't be combined with anything else.
Using a pre-Oracle 11 pivot technique, the following works:
WITH     got_pairs     AS
     SELECT       a.product_type               AS product_a
     ,       NVL (b.product_type, a.product_type)     AS product_b
     FROM            cust_product     a
     LEFT OUTER JOIN     cust_product     b  ON  a.customer     = b.customer
                            AND     a.product_type != b.product_type
SELECT       product_a     AS product_type
,       COUNT (CASE WHEN product_b = 'DVD'    THEN 1 END)     AS dvd
,       COUNT (CASE WHEN product_b = 'Tape'   THEN 1 END)     AS dvd
,       COUNT (CASE WHEN product_b = 'Bluray' THEN 1 END)     AS dvd
FROM       got_pairs
GROUP BY  product_a
ORDER BY  CASE  product_a
          WHEN  'DVD'     THEN  1
          WHEN  'Tape'     THEN  2
          WHEN  'Bluray'     THEN  3
       END
;Notice that the sub-query got_pairs is the same in both queries.
Thanks for posting the CREATE TABLE and INSERT statements; that's very helpful!
Edited by: Frank Kulash on May 29, 2011 4:05 PM
Added Oracle 9 query.