1. PL/SQL Agenda: Basic PL/SQL block structure
Example procedures and functions
Executing PL/SQL from SQL*Plus
Exceptions
Packages

2. More PL/SQL - block structureIS
BEGIN
EXCEPTION
END;
-- defines type of block (procedure, function, anonymous) and the way it is called
-- declare any variables used in the block
-- use variables and other PL/SQL objects to perform actions
-- handle any problems that arise during execution of the block
Block Header
Declaration Header
REQUIRED
Execution Section
Exception Section

3. PL/SQL… Is not case sensitive Uses the same datatypes as SQL
Also has boolean, record, table, varray and LOB
Allows reference datatypes
%type and %rowtype
Allows comments
/* and */ for multiline and -- for single line
Uses := for assignment
Uses ; to indicate end of line (instruction)

4. PL/SQL - example DECLARE loop_count BINARY_INTEGER := 0; BEGIN LOOP
INSERT INTO count_table VALUES (loop_count);
DBMS_output.put_line
(‘loop_count is ’ || to_char(loop_count));
loop_count := loop_count + 1;
EXIT WHEN loop_count = 6;
END LOOP;
END;

5. Scott.GIVE_RAISE CREATE OR REPLACE PROCEDURE give_raise (
p_deptno IN number,
p_raise_percent IN number ) AS
BEGIN
update emp
set sal = sal + (sal * p_raise_percent * .01)
where deptno = p_deptno;
commit;
END give_raise;

6. Another example…
CREATE OR REPLACE FUNCTION get_company_name (comp_id_in IN company.id%TYPE)
RETURN varchar2 IS
cname company.name%TYPE;
BEGIN
SELECT name INTO cname FROM company
WHERE id = comp_id_in;
RETURN cname;
EXCEPTION
WHEN NO_DATA_FOUND THEN
RETURN NULL;
WHEN OTHERS
DBMS_OUTPUT.PUT_LINE (‘error code= ‘ || SQLCODE);
DBMS_OUTPUT.PUT_LINE (‘error msg= ‘ || SQLERRM);
END;

7. Cursors Implicit Explicit Created automatically in Oracle
Don’t need to be declared
Can be used only when 1 and only 1 record is returned
Explicit
Declared in declaration section
attributes specifying the state of the cursor
%notfound, %found, %rowcount, %isopen
Use “cursor for loop” to work with
FOR item IN cursor LOOP … END LOOP;
Substitute cursor name and row variable for cursor and item
Opens cursor and fetches results into cursor automatically

8. Another PL/SQL example…
DECLARE
current_bldg_code VARCHAR2(5);
CURSOR location_cursor IS
SELECT room, capacity
FROM location
WHERE bldg_code = current_bldg_code
FOR UPDATE of capacity;
location_row location_cursor%rowtype;
BEGIN
current_bldg_code := ‘LIB’;
FOR location_row IN location_cursor LOOP
UPDATE location
Set capacity = capacity +1
WHERE CURRENT OF location_cursor;
END LOOP;
COMMIT;
END;
From Morrison & Morrison, p. 247

9. Using PL/SQL - functions
From SQL*Plus command line
Functions require that you create a variable in SQL*Plus to hold the value returned first
variable cname varchar2(100)
then
select get_company_name(1) from dual;
valid commands to execute stored function f1 returns number) from SQL*Plus.
exec :a := f1;
execute :a := f1;
call f1() into :a;
begin :a := f1; end;
select f1 from dual;

10. Using PL/SQL - procedures
From SQL*Plus command line
Procedures don’t return a value, so
Execute Give_raise(20,10);
valid commands to execute stored procedure p1 from SQL*Plus.
exec p1;
execute p1;
call p1();
begin p1; end;

11. Debugging PL/SQL
Remember the Oracle error message facility – will help figure out the problem
Comment out lines that may be causing problems
Use dbms_output.put_line to show variable values
Fix from the top down – 1 error may cause multiple error messages
Data dictionary views: user_errors, user_source

12. Exception types NO_DATA_FOUND TOO_MANY_ROWS DUP_VAL_ON_INDEX And more…
Create your own

13. Another PL/SQL example…
FUNCTION build_name (name_in IN VARCHAR2, sex_in IN VARCHAR2)
RETURN VARCHAR2 IS
unknown_sex EXCEPTION;
name_out VARCHAR2(100);
BEGIN
IF sex_in =‘M’ THEN name_out := ‘Mr. ‘ || name_in;
ELSIF sex_in =‘F’ THEN name_out := ‘Ms. ‘ || name_in;
ELSE
RAISE unknown_sex
END IF;
RETURN name_out;
EXCEPTION
WHEN unknown_sex THEN
DBMS_OUTPUT.PUT_LINE
(‘Unable to determine gender of individual!’);
END;

14. Packages Structure of Packages Advantages of Packages
package header vs. package body
Advantages of Packages
invalidated objects
hiding details of code
code maintainability

15. Oracle provided packages
DBMS_output
DBMS_job
DBMS_pipe
And more…
Set serveroutput on size 4000;
Dbms_output.put_line (‘text to be displayed’);