Using PL/SQL Arrays and Bulk Collects

Description

Your task is to take a sub-optimal PL/SQL code routine and re-write to using the bulk collect and FORALL features. As we emphasized, using BULK COLLECT and FORALL can make PL/SQL run faster, often by an order of magnitude.

Procedure

In our example, we create a table called title_caps, which will store the uppercase title for all titles in the book table.  Run this definition on your system:

drop table title_caps;create table title_caps (uppercase_title varchar2(80));

The PL/SQL program below is a simple routine that:

1 – Defines a PL/SQL table (an array) to hold the titles

DECLARE   type t_name is table of book.book_title%type index by binary_integer;   title_rec t_name;   i binary_integer := 1;

2 – Declares a cursor, and fetches the rows into the array

DECLARE   cursor c1 is select book_title from book;BEGIN   open c1;   loop      --*****************************************      -- Load the PL/SQL table, one row at a time      --*****************************************      fetch c1 into title_rec(i);       exit when c1%NOTFOUND;      i := i + 1;   end loop;

3 – Inserts into the new table from the array, one row at a time

for i in 1..title_rec.COUNTloop   --****************************************************   -- Add rows to the new title_caps table, one at a time   --****************************************************

   insert into title_caps values (upper(title_rec(i)));end loop; 

Here is the whole code snippet.  Your challenge is to rewrite this code using the BULK COLLECT and FORALL operators.  Copy this code to your server as slow_collect.sql in your c:\Burleson directory

delete from title_caps;

DECLARE   type t_name is table of book.book_title%type index by binary_integer;   title_rec t_name;   i binary_integer := 1;   cursor c1 is select book_title from book;BEGIN   open c1;   loop      --*****************************************      -- Load the PL/SQL table, one row at a time      --*****************************************      fetch c1 into title_rec(i);       exit when c1%NOTFOUND;      i := i + 1;   end loop; 

close c1; 

dbms_output.Put_line('Old Book Titles:');

for i in 1..title_rec.COUNTloop   --****************************************************   -- Add rows to the new title_caps table, one at a time   --****************************************************   insert into title_caps values (upper(title_rec(i)));end loop;

end;/

select * from title_caps; 

Your new code will be called bulk_collect.sql, and it will have the following features:

* Write a BULK COLLECT statement to load your PL/SQL table in a single operation.

* Use a FORALL operator to insert the rows into the title_caps table in a single operation.

Hint:  If you have any problems, use Google to locate PL/SQL syntax.  For example, a Google search of PL/SQL FORALL will instantly give you the forall syntax.

Once completed, e-mail your bulk_collect.sql code to your instructor.

ANSWER:

drop table new_title;create table new_title (book_title varchar2(80)); 

DECLARE   type t_name is table of book.book_title%type index by binary_integer;   title_rec t_name;   i binary_integer := 1;BEGIN   select      book_title   BULK COLLECT      into title_rec   from      book;

FORALL i in title_rec.first..title_rec.last   insert into new_title values (upper (title_rec (i)));end;/select * from new_title;