SQL: The PIVOT clause

The PIVOT clause allow you to display data of different categories in one row. It is a new feature added in 11g.

Let's say you have the following Inventory table.

StoreName             Product           Quantity
----------------         --------------      ----------
store 1                    Apple               100
store 1                    Banana             350
store 1                    Pineapple         300
store 2                    Apple               150
store 2                    Banana              300
store 2                    Pineapple          250
store 3                    Apple                200
store 3                    Banana              180
store 3                    Pineapple           260

SQL> select * from Inventory where not StoreName = 'store 3' order by StoreName;

Output:

StoreName             Product           Quantity
----------------         --------------      ----------
store 1                    Apple               100
store 1                    Banana             350
store 1                    Pineapple         300
store 2                    Apple               150
store 2                    Banana              300
store 2                    Pineapple          250

If you want to view all the products of each store in one row, the PIVOT clause will help.

SQL> select * from
           (
                  select StoreName, Product, Quantity from Inventory
           )
            PIVOT
           (
                   sum(Quantity) as Qty for Product in ('Apple' as Apple, 'Banana' as Banana, 'Pineapple' as Pineapple)
            )
            where not StoreName = 'store 3' order by StoreName;

Output:

StoreName         Apple_Qty         Banana_Qty        Pineapple_Qty
--------------        -------------          --------------          ----------------
store 1                100                     350                       300
store 2                150                     300                       250

SQL> select * from
           (
                 select StoreName, Quantity from Inventory
            )
            PIVOT
            (
                     sum(Quantity) for StoreName in ('store 1', 'store 2', 'store 3')
            );

Output:

store 1           store 2           store 3
---------         ---------           ---------
750               700                 640

SQL> select StoreName, sum(Quantity) as "Total Quantity" from Inventory group by StoreName;

Output:

StoreName           Total Quantity
-------------            ------------------
store 1                   750
store 2                    700
store 3                   640

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