Oracle PL/SQL for DBAs

Running the Function

The function is executed using a SQL SELECT statement that is passed another SQL SELECT statement. I know that may still take some getting used to, but believe me—it’s worth checking out. Here’s the SQL used to run the function:

    /* File on web: repeat_orders.sql */
    SQL> SELECT *
      2    FROM TABLE(repeat_order_finder(CURSOR(
      3                 SELECT order_number,
      4                        order_date,
      5                        region_id,
      6                        type_id,
      7                        location_id
      8                   FROM orders
      9                  WHERE order_date >= SYSDATE - 30
     10               )))
     11  /

     REGION_ID LOCATION_ID FIRST_TYPE_ID REPEAT_TYPE_ID
    ---------- ----------- ------------- --------------
             1           1             1              2
             2           2             2              3
             3           3             3              4
             4           4             4              5
             4           4             4              5
             5           5             5              6
             6           6             6              7
             7           7             7              8
             8           8             8              9
             9           9             9             10
            10          10            10             11

    11 rows selected.

The result set is treated just as if it came from an Oracle table or view. Criteria could be applied to limit the result set—for example, “WHERE first_type_id = 3”. Even more exciting is the fact that the results of a somewhat convoluted business process are available as a simple SQL query upon which reports can easily be built. All of the business logic to assemble the result set is done in the database.

Pipelining the function serves records up to be processed right away, saving even more valuable time.