4. PL/SQL
PL / SQL
PL/SQL is the procedural extension to SQL with design feature
of programming languages.
Data Manipulation and Query statements of SQL are included
within procedural units of code.
Place reusable PL/SQL code in libraries to be shared between
application to all users.
7/5/12 7/5/12 4
5. PL/SQL
PL/SQL Versions
Year Oracle PL/SQL Characteristics
1991 6 1.0 Programming Language
1992 7 2.0 Stored procedure, functions, packages,
PL/SQL tables, DBMS_OUTPUT, DBMS_PIPE
1994 7.1 2.1 Programmer defined subtypes, DBMS_SQL,
Stored functions inside SQL statement.
1995 7.3 2.3 UTL_FILE, Cursor variables, remote dependency
1997 8 8.0 LOB, Object-Oriented design, Advanced Queuing,
Collections (VARRAY , nested table)
1998 8i 8.1 Native Dynamic SQL (EXECUTE IMMEDIATE), Support for Java,
Autonomous Transaction
2000 9i R1 9.0 Native Compilation as C code, Inheritance in object types,
multi-level collections, CASE expression
2002 9i R2 9.2 Oracle Text CTXXPATH, XML, index-by tables indexed by
VARCHAR2, record-based DML,
UTL_FILE (allows to copy, remove, and rename files).
2004 10g 10.0 Regular Expression, DBMS_WARNING package,
BINARY_FLOAT, BINARY_DOUBLE, DBMS_LOB (128 TB), String literal.
7/5/12 7/5/12 5
6. PL/SQL
* Block - The basic program unit in PL/SQL
* Blocks contain sets of instructions to perform. (must contain one command)
* You can declare variables.
* You can program with Control Structures, IF-THEN-ELSE, LOOP...
* Error handling functionality.
* Nest sub-block inside large block to build powerful program.
* Single line Comment --
* Multiple line Comments /* */
* A slash ( / ) runs the PL/SQL block.
DECLARE (Optional)
Variables, cursors, user-defined exception
BEGIN (Mandatory)
SQL & PL/SQL statements
EXCEPTION (Optional)
Actions to perform when error occur
END; (Mandatory)
/
7/5/12 7/5/12 6
7. PL/SQL
Anonymous Procedure Function
[DECLARE] PROCEDURE Name FUNCTION Name
IS RETURN Datatype
IS
BEGIN BEGIN BEGIN
-- statements -- statements -- statements
RETURN
[EXCEPTION] [EXCEPTION] [EXCEPTION]
END; END; END;
7/5/12 7/5/12 7
8. PL/SQL
Oracle tools, like Developer, Oracle Forms have their own PL/SQL
engine, which is independent of the engine present in the Oracle Server.
The engine filters out SQL statement and sends them
individually to the SQL statement executor in the Oracle Server.
PL/SQL engine, processes remaining Procedural statements.
PL / SQL engine
PL/SQL PL/SQL Procedural statement
block block executor
SQL statement executor
Oracle Server
7/5/12 7/5/12 8
11. PL/SQL
Use of Variables
Temporary storage of data
Manipulation of stored values
Reusability
Handling Variables
Declare and initialize variable in the declaration section.
Assign new values to variables in the executable section.
View results through output variables
7/5/12 7/5/12 11
12. PL/SQL
Types of Variables
PL / SQL
Scalar (hold a single value) - number, date, binary_integer,
boolean (true, false, null),
timestamp…
Composite (group of value) - records, cursors…
Reference (other program) - pointers
LOB (Large objects) - graphics, movies
Non - PL / SQL
Bind and host variables - global values
7/5/12 7/5/12 12
13. PL/SQL
* Follow naming conventions.
* Declare one identifier per line.
* Initialize identifiers by using the assignment operator ( := )
identifier [CONSTANT] datatype [NOT NULL]
[ := | DEFAULT expr];
DECLARE
v_hiredate DATE;
v_deptno NUMBER(2) NOT NULL := 10;
v_location VARCHAR2(12) := ‘Atlanta’;
c_comm CONSTANT NUMBER := 1400;
v_count BINARY_INTEGER := 0;
v_total_sal NUMBER(9,2) := 0;
v_orderdate DATE := SYSDATE + 7;
v_valid BOOLEAN NOT NULL := TRUE;
variables
7/5/12 7/5/12 13
14. PL/SQL
* Declare variable according to :
-- A database column definition
-- Another previously declared variable
identifier table.column_name%TYPE ;
DECLARE
v_name employees.last_name%TYPE ;
v_balance NUMBER(7,2);
v_min_balance v_balance%TYPE := 10;
* Boolean (TRUE - FALSE - NULL)
v_sal1 := 50000; DECLARE
v_sal2 := 60000; v_flag BOOLEAN := FALSE;
BEGIN
v_sal1 < v_sal2 v_flag := TRUE;
this evaluates to TRUE END;
7/5/12 7/5/12 14
15. PL/SQL
• Large OBjects 4GB
-- to store unstructured data (graphics, video, soundwave)
-- CLOB Character Large OBject lengthy text
-- BLOB Binary Large OBject Graphics, Photos
-- BFILE Binary FILE Movie
-- NCLOB National Language Other Language
Character Large OBject
7/5/12 7/5/12 15
18. PL/SQL
DECLARE
x NUMBER;
y NUMBER;
BEGIN
....... Scope of x , y
DECLARE
z NUMBER;
BEGIN
z := x ; Scope of z
END;
.......
y := z ;
END;
A block can look up to the enclosing block.
A block cannot look down to the enclosed block.
7/5/12 7/5/12 18
19. PL/SQL
The qualifier can be the label of the enclosing block.
Qualify an identifier by using the block label prefix.
<<abc>>
DECLARE
birthdate DATE;
BEGIN
DECLARE
birthdate DATE;
..
abc.birthdate := TO_DATE(‘03-AUG-2004’,’DD-MON-YYYY’);
END;
..
END;
7/5/12 7/5/12 19
20. PL/SQL
To reference a Bind Variable, prefix with colon ( : )
VARIABLE g_monthly_sal NUMBER
DEFINE p_annual_sal = 5000
SET VERIFY OFF
DECLARE
v_sal NUMBER(9,2) := &p_annual_sal;
BEGIN
:g_monthly_sal := v_sal / 12;
END;
/
PRINT g_monthly_sal
7/5/12 7/5/12 20
21. PL/SQL
* Retrieve data from the database with a SELECT statement.
* Queries must return only one row.
SELECT select_list
INTO {variable_name[, variable_name]...
| record_name}
FROM table
[WHERE condition];
* Retrieve the department no and location no, for department Sales.
DECLARE
v_deptno NUMBER(4);
v_locid NUMBER(4);
BEGIN
SELECT department_id, location_id
INTO v_deptno, v_locid
FROM departments
WHERE department_name = ‘Sales’;
END;
7/5/12 7/5/12 21
22. PL/SQL
An Oracle-supplied packaged procedure
To display data to screen
Enable with SET SERVEROUTPUT ON
SET SERVEROUTPUT ON
DEFINE p_annual_sal = 6000
DECLARE
v_sal NUMBER(9,2) := p_annual_sal;
BEGIN
v_sal := v_sal/12;
DBMS_OUTPUT.PUT_LINE (‘The monthly salary is’ ||
TO_CHAR(v_sal));
END;
/
7/5/12 7/5/12 22
23. PL/SQL
* Display the sum of the salaries for all employees in the specified department.
SET SERVEROUTPUT ON
DECLARE
v_sum_sal NUMBER(10,2);
BEGIN
SELECT sum(salary)
INTO v_sum_sal
FROM employees
WHERE department_id = 30;
DBMS_OUTPUT.PUT_LINE(‘The sum salary is ‘
|| TO_CHAR(v_sum_sal));
END;
/
.. ..
BEGIN
Analyze the result SELECT salary
INTO v_sum_sal
Why ? FROM employees
WHERE department_id = 30;
7/5/12 7/5/12 23
24. PL/SQL
* The following DELETE statement removes all employees,
where last name is not just ‘King’, because Oracle assumes
that both last_name(s) in the WHERE clause refer to the
database column.
DECLARE
last_name VARCHAR2(25) := ‘King’;
BEGIN
DELETE FROM emp_copy
WHERE last_name = last_name ;
END;
7/5/12 7/5/12 24
26. PL/SQL
BEGIN
INSERT INTO employees
(employee_id, first_name, last_name, email,
hire_date, job_id, salary)
VALUES ( 27 , ‘Ruth’, ‘Cores’, ‘RCORES’,
sysdate, ‘AD_ASST’ 9000);
END;
DECLARE
v_sal_inc employees.salary%TYPE := 800;
BEGIN
UPDATE employees
SET salary = salary + v_sal_inc
WHERE job_id = ‘ST_CLERK’;
COMMIT;
END;
DECLARE
v_deptno employees.department_id%TYPE := 80;
BEGIN
DELETE FROM employees
WHERE department_id = v_deptno ;
END;
7/5/12 7/5/12 26
27. PL/SQL
* Cursor is a private SQL work area for each user.
* Two Types :
Implicit Cursor - Automatically created if any SQL statement is executed.
Explicit Cursor - Can Create by programmer.
Attributes are used to test the outcome of the result.
SQL%ROWCOUNT Number of rows affected by the recent SQL statement
SQL%FOUND Boolean attribute that evaluates TRUE if the recent
SQL statement affects one or more rows.
SQL%NOTFOUND Boolean attribute that evaluates TRUE if the recent
SQL statement does not affects any rows.
SQL%ISOPEN Always evaluates FALSE because, implicit cursors are closed
immediately after they are executed.
7/5/12 7/5/12 27
29. PL/SQL
DECLARE
v_weight NUMBER(3) := 600;
v_message VARCHAR2(99) := ‘ Product 10012’;
BEGIN
DECLARE
v_weight NUMBER(3) := 1;
v_message VARCHAR2(90) := ‘Product 11001’;
v_new_locn VARCHAR2(50) := ‘Europe’;
BEGIN
v_weight := v_weight + 1;
v_new_locn := ‘Western ‘ || v_new_locn;
1
END;
v_weight := v_weight + 1;
v_message := v_message || ‘ is in stock’;
v_new_locn := ‘Western ‘ || v_new_locn;
2
END;
The value of V_WEIGHT at position 1 -> 2
The value of V_NEW_LOCN at position 1 -> Western Europe
The value of V_WEIGHT at position 2 -> 601
The value of V_MESSAGE at position 2 -> Product 10012 is in stock
The value of V_NEW_LOCN at position 2 -> Illegal because, not visible outside the sub-block
7/5/12 7/5/12 29
30. PL/SQL
Class Exercise 1
<<abc>>
DECLARE
v_sal NUMBER(7,2) := 60000;
v_comm NUMBER(7,2) := v_sal * 0.20;
v_message VARCHAR2(90) := ‘ eligible for commission ’;
BEGIN
DECLARE
v_sal NUMBER(7,2) := 50000;
v_comm NUMBER(7,2) := 0;
v_total_comp NUMBER(7,2) := v_sal * v_comm;
BEGIN
v_message := ‘CLERK not ’|| v_message;
abc.v_comm := v_sal * 0.30;
1
END;
v_message := ‘SALESMAN’ || v_message;
2
END;
The value of V_MESSAGE at position 1 The value of V_TOTAL_COMP at position 2
The value of V_COMM at position 1 The value of V_COMM at position 2
The value of ABC.V_COMM at position 1 The value of V_MESSAGE at position 2
7/5/12 7/5/12 30
31. PL/SQL
Summary
Nested Blocks and Scope Variables
Qualify and Identifier
SELECT statement in PL/SQL
Using Bind Variable
DBMS_OUTPUT.PUT_LINE
Retrieve Data
Naming Convention
Functions in PL/SQL
Insert / Update / Delete
Cursors
7/5/12 7/5/12 31
33. PL/SQL
* You can change the logical execution of statements using IF
statements and LOOP control structures
IF condition THEN
statements;
[ELSIF condition THEN
statements;]
[ELSE
statements;]
END IF;
Eg., If the employee name is Vargas, set job id to SA_REP
and set department number to 80
IF UPPER(v_last_name) = ‘VARGAS’ THEN
v_job := ‘SA_REP’
v_deptno := 80;
END IF;
7/5/12 7/5/12 33
34. PL/SQL
Eg., If the last name is Vargas and the salary is more than 6500,
Set the department number to 60.
IF v_ename = ‘Vargas’ AND salary > 6500 THEN
v_deptno := 60;
END IF;
..
Set a Boolean flag to TRUE if the hire date is greater than Five years; other wise,
set the Boolean flag to FALSE.
DECLARE
v_hire_date DATE := ’12-DEC-1990’;
v_five_years BOOLEAN;
BEGIN
IF MONTHS_BETWEEN(sysdate,v_hire_date)/12 > 5 THEN
v_five_years := TRUE;
ELSE
v_five_years := FALSE;
END IF;
END;
/
7/5/12 7/5/12 34
35. PL/SQL
IF condition1 THEN
statements1;
ELSIF condition2 THEN
statements2;
ELSE
statements3;
END IF;
Determine an employee’s bonus based upon the employee’s department.
...
IF v_deptno = 10 THEN
v_bonus := 5000;
ELSIF v_deptno = 80 THEN
v_bonus := 7500;
ELSE
v_bonus := 2000;
...
END IF;
7/5/12 7/5/12 35
36. PL/SQL
CASE expression selects a result and returns it.
SET SERVEROUTPUT ON
DECLARE
v_grade CHAR(1) := ‘A’;
v_appraisal VARCHAR2(20);
BEGIN
v_appraisal := CASE v_grade WHEN ‘A’ THEN ‘Excellent’
WHEN ‘B’ THEN ‘Very Good’
WHEN ‘C’ THEN ‘Good’
ELSE ‘No such grade’
END;
DBMS_OUTPUT.PUT_LINE (‘Grade: ’ || v_grade ||
‘ Appraisal’ || v_appraisal);
END;
/
7/5/12 7/5/12 36
38. PL/SQL
• LOOPs repeat a statement or sequence of statements multiple times.
• Types of LOOP
Basic LOOP - Perform repetitive actions without overall conditions.
FOR loop - Perform iterative control of actions based on count.
WHILE loop - perform iterative control based on a condition.
7/5/12 7/5/12 38
39. PL/SQL
• A basic LOOP allows execution of its statements atleast once, even if the
condition already met upon entering the loop.
LOOP
statement1;
EXIT [WHEN condition];
END LOOP;
DECLARE
v_country_id locations.country_id%TYPE := ‘CA’;
v_location_id locations.location_id%TYPE;
v_counter NUMBER(2) := 1;
v_city locations.city%TYPE := ‘Montreal’;
BEGIN
SELECT MAX(location_id) INTO v_location_id
FROM locations WHERE country_id = v_country_id;
LOOP
INSERT INTO locations(location_id, city, country_id)
VALUES((v_location_id + v_counter),v_city,v_country_id);
v_counter := v_counter + 1;
EXIT WHEN v_counter > 3;
END LOOP;
END;
7/5/12 7/5/12 39
40. PL/SQL
• A WHILE Loop repeats sequence of statements until the controlling
condition is no longer TRUE.
WHILE condition LOOP
statement1..;
END LOOP;
DECLARE
v_country_id locations.country_id%TYPE := ‘CA’;
v_location_id locations.location_id%TYPE;
v_counter NUMBER(2) := 1;
v_city locations.city%TYPE := ‘Washington’;
BEGIN
SELECT MAX(location_id) INTO v_location_id
FROM locations WHERE country_id = v_country_id;
WHILE v_counter <= 3 LOOP
INSERT INTO locations(location_id, country_id)
VALUES((v_location_id + v_counter),v_city,v_country_id);
v_counter := v_counter + 1;
END LOOP;
END;
7/5/12 7/5/12 40
41. PL/SQL
• A FOR Loop is used to test for the number of iterations.
FOR counter IN [REVERSE] lower_bound..upper_bound LOOP
statement1..;
statement2..; Implicitly j IN -5..5
declared k IN REVERSE first..last
END LOOP;
step IN 0..TRUNC(high/low) * 2
DECLARE
v_country_id locations.country_id%TYPE := ‘CA’;
v_location_id locations.location_id%TYPE;
v_city locations.city%TYPE := ‘Paris’;
BEGIN
SELECT MAX(location_id) INTO v_location_id
FROM locations WHERE country_id = v_country_id;
FOR i IN 1..3 LOOP
INSERT INTO locations(location_id, country_id)
VALUES((v_location_id + i), v_city, v_country_id);
v_counter := v_counter + 1;
END LOOP;
END;
7/5/12 7/5/12 41
42. PL/SQL
Specify a different increment (5 instead of 1 for example). Inside the FOR loop,
simply multiply each reference to the loop counter by the new increment. In the
following example, you assign today's date to elements 5, 10, and 15 of an
index-by table:
DECLARE
TYPE DateList IS TABLE OF DATE INDEX BY BINARY_INTEGER;
dates DateList;
k CONSTANT INTEGER := 5; -- set new increment
BEGIN
FOR j IN 1..3 LOOP
dates(j*k) := SYSDATE; -- multiply loop counter by increment
END LOOP;
...
END; FOR ctr IN 1..10 LOOP
IF NOT finished THEN
INSERT INTO ... VALUES (ctr, ...); -- OK
factor := ctr * 2; -- OK
ELSE
ctr := 10; -- not allowed
END IF;
END LOOP;
7/5/12 7/5/12 42
43. PL/SQL
• Nest loops to multiple levels.
• Use labels to distinguish between blocks and loops.
• Exit the outer loop with the EXIT statement that references the label.
.. .. ..
BEGIN
<<Outer_loop>>
LOOP
v_counter := v_counter + 1;
EXIT WHEN v_counter > 10; -- leaves both loops
<<Inner_loop>>
LOOP
...
EXIT Outer_loop WHEN total_done = ‘YES’;
-- leaves both loops
EXIT WHEN inner_done = ‘YES’;
-- leaves inner loop only
.. ..
END LOOP Inner_loop;
.. ..
END LOOP Outer_loop;
END;
7/5/12 7/5/12 43
44. PL/SQL
• Create the MESSAGES table with column results varchar2(60)
• Insert the numbers 1 to 10 excluding 6 and 8
• Commit before the end of the block
BEGIN
FOR i IN 1..10 LOOP
IF i = 6 or i = 8 THEN
null;
ELSE
INSERT INTO messages(results)
VALUES (i);
END IF;
COMMIT;
END LOOP;
END;
/
7/5/12 7/5/12 44
45. PL/SQL
Summary
LOOP IF condition1 THEN
statement1; statements1;
EXIT [WHEN condition]; ELSIF condition2 THEN
END LOOP; statements2;
ELSE
statements3;
END IF;
CASE
WHILE condition LOOP
statement1..;
BOOLEAN
END LOOP;
FOR counter IN [REVERSE] lower_bound..upper_bound LOOP
statement1..;
statement2..;
END LOOP;
7/5/12 7/5/12 45
47. PL/SQL
* Declare a variable according to the collection of columns in a database table
or view.
* Prefix %ROWTYPE with the database table.
* Fields in the record take their names and data types from the columns of the
table or view
DEFINE employee_no = 124
DECLARE
emp_rec employees%ROWTYPE;
BEGIN
SELECT * INTO emp_rec FROM employees
WHERE employee_id = &employee_no;
INSERT INTO retired_emps(empno, ename, job, mgr,
hiredate, leavedate, sal, comm, deptno)
VALUES (emp_rec.employee_id, emp_rec.last_name,
emp_rec.job_id, emp_rec.manager_id,
emp_rec.hire_date, SYSDATE, emp_rec.salary,
emp_rec.commission_pct, emp_rec.department_id);
COMMIT;
END;
/
7/5/12 7/5/12 47
48. PL/SQL
Write a PL/SQL block to print information about a given country
DEFINE p_countryid = CA
DECLARE
country_record countries%ROWTYPE;
BEGIN
SELECT *
INTO country_record
FROM countries
WHERE country_id = UPPER(‘&p_countryid’);
DBMS_OUTPUT.PUT_LINE (
‘ Country Id: ‘|| country_record.country_id ||
‘ Country Name: ‘|| country_record.country_name||
‘ Region: ‘|| country_record.region_id);
END;
/
7/5/12 7/5/12 48
50. PL/SQL
Every SQL statement executed by the Oracle Server has an individual cursor
associated with it.
Implicit Cursor : Declared for all DML and PL/SQL SELECT statements.
Explicit Cursor : Declared and named by the programmer.
Use CURSOR to individually process each row returned by a
multiple-row SELECT Statement.
The set of rows returned by a multiple-row query is called active set.
No
Yes
DECLARE OPEN FETCH EMPTY? CLOSE
Create a Identify the Lead the Test for existing Release the
named SQL active set current row rows active set.
area into
variables Return to FETCH if
rows are found
7/5/12 7/5/12 50
51. PL/SQL
* Retrieve the first 10 employees one by one.
SET SERVEROUTPUT ON
DECLARE
v_empno employees.employee_id%TYPE;
v_ename employees.last_name%TYPE;
CURSOR emp_cursor IS
SELECT employee_id, last_name FROM employees;
BEGIN
OPEN emp_cursor;
FOR i IN 1..10 LOOP
FETCH emp_cursor INTO v_empno, v_ename;
DBMS_OUTPUT.PUT_LINE(TO_CHAR(v_empno)||’ ‘||v_ename);
END LOOP;
CLOSE emp_cursor;
END;
7/5/12 7/5/12 51
52. PL/SQL
cname%ROWCOUNT Number Evaluates to the total number of rows returned so for
cname%FOUND Boolean Evaluates to TRUE if the most recent fetch returns a row.
cname%NOTFOUND Boolean Evaluates to TRUE if the most recent fetch does not
return a row.
cname%ISOPEN Boolean Evaluates TRUE if the cursor is open
IF NOT emp_cursor%ISOPEN THEN LOOP
OPEN emp_cusor; FETCH c1 INTO my_ename, my_sal;
END IF;
LOOP EXIT WHEN c1%NOTFOUND;
FETCH emp_cursor.. .. .. ..
END LOOP;
LOOP
FETCH c1 INTO my_deptno;
IF c1%ROWCOUNT > 10 THEN
.. ..
END IF;
.. ..
END LOOP;
7/5/12 7/5/12 52
53. PL/SQL
* Retrieve the first 10 employees one by one by using attributes.
SET SERVEROUTPUT ON
DECLARE
v_empno employees.employee_id%TYPE;
v_ename employees.last_name%TYPE;
CURSOR emp_cursor IS
SELECT employee_id, last_name FROM employees;
BEGIN
OPEN emp_cursor;
LOOP
FETCH emp_cursor INTO v_empno, v_ename;
EXIT WHEN emp_cursor%ROWCOUNT > 10 OR
emp_cursor%NOTFOUND;
DBMS_OUTPUT.PUT_LINE(TO_CHAR(v_empno)||’ ‘||v_ename);
END LOOP;
CLOSE emp_cursor;
END;
7/5/12 7/5/12 53
54. PL/SQL
* Process the rows of the active set by fetching values into PL/SQL RECORD.
Populate to the table temp_list.
DECLARE
CURSOR emp_cursor IS
SELECT employee_id, last_name FROM employees;
emp_record emp_cursor%ROWTYPE;
BEGIN
OPEN emp_cursor;
LOOP
FETCH emp_cursor INTO emp_record;
EXIT WHEN emp_cursor%NOTFOUND;
INSERT INTO temp_list (emp_id, ename)
VALUES (emp_record.employee_id,
emp_record.last_name);
END LOOP;
COMMIT;
CLOSE emp_cursor;
END;
7/5/12 7/5/12 54
55. PL/SQL
* Implicit Open, Fetch, and Close occurs
The record is implicitly declared.
Retrieve employee one by one who is working in department
80
SET SERVEROUTPUT ON
DECLARE
CURSOR emp_cursor IS
SELECT last_name, department_id FROM employees;
BEGIN
FOR emp_record IN emp_cursor LOOP
-- implicit open fetch occur
IF emp_record.department_id = 80 THEN
DBMS_OUTPUT.PUT_LINE(‘Employee ‘ ||
emp_record.last_name ||
‘ works in the Sales Dept.‘);
END IF;
END LOOP; -- implicit close
END;
7/5/12 7/5/12 55
56. PL/SQL
* No need to declare the cursor, if FOR loop is used
Same result as previous Slide :
Retrieve employee one by one who is working in department
80
SET SERVEROUTPUT ON
BEGIN
FOR emp_record IN
(SELECT last_name, department_id FROM employees)
LOOP
-- implicit open fetch occur
IF emp_record.department_id = 80 THEN
DBMS_OUTPUT.PUT_LINE(‘Employee ‘ ||
emp_record.last_name ||
‘ works in the Sales Dept.‘);
END IF;
END LOOP; -- implicit close
END;
7/5/12 7/5/12 56
57. PL/SQL
* Pass parameter values to a cursor using WHERE, and Open an explicit cursor
several times with a different times with the different active set each time.
SET SERVEROUTPUT ON
DECLARE
CURSOR emp_cursor (p_dno NUMBER) IS
SELECT employee_id, last_name FROM employees
WHERE department_id = p_dno;
BEGIN
FOR emp_record IN emp_cursor(50) LOOP
DBMS_OUTPUT.PUT_LINE(‘Employee ‘ ||
emp_record.employee_id||’ ‘|| emp_record.last_name ||
‘ works in 50‘);
END LOOP;
FOR emp_record IN emp_cursor(60) LOOP
DBMS_OUTPUT.PUT_LINE(‘Employee ‘ ||
emp_record.employee_id||’ ‘|| emp_record.last_name ||
‘ works in 60‘);
END LOOP;
END;
/
7/5/12 7/5/12 57
58. PL/SQL
FOR UPDATE Clause
-- Use explicit locking to deny access for the duration of a transaction.
-- Lock the rows before the update or delete.
-- NOWAIT keyword tells not to wait if requested rows have been locked by another user.
WHERE CURRENT OF cursor; To reference the current row from an explicit cursor.
DECLARE
CURSOR sal_cursor IS
SELECT e.department_id, employee_id, last_name, salary
FROM employees e, departments d
WHERE d.department_id = e.department_id AND d.department_id=60
FOR UPDATE OF salary NOWAIT;
BEGIN
FOR emp_record IN sal_cursor
LOOP
IF emp_record.salary < 5000 THEN
UPDATE employees
SET salary = emp_record.salary * 1.10
WHERE CURRENT OF sal_cursor ;
END IF;
END LOOP;
END;
7/5/12 7/5/12 58
59. PL/SQL
Summary
Use CURSOR to individually process each row returned by a
multiple-row SELECT Statement.
Implicit Cursor : Declared for all DML and PL/SQL SELECT statements.
Explicit Cursor : Declared and named by the programmer.
Using Attributes
Fetching values into PL/SQL RECORD
FOR loop - Implicit Open, Fetch, and Close occurs
The record is implicitly declared.
Cursor with Parameters.
FOR UPDATE OF . . NOWAIT WHERE CURRENT OF
7/5/12 7/5/12 59
61. PL/SQL
An exception is an identifier in the PL/SQL that is raised during execution.
How it is raised ? [DECLARE]
- An Oracle error occurs.
- You raise it explicitly. BEGIN
Exception/Error is Raised
How do you handle it ?
- Trap it with handler. EXCEPTION
Error is Trapped
- Propagate it to the calling environment.
END;
Types of Exceptions
User activity
Predefined apprx. 20 errors ( < -20000 ) Declared Raised
eg. ORA-01422 TOO_MANY_ROWS NO
NO
Non-Predefined Any other standard ( < -20000 ) YES NO
Oracle Server Error
User Defined A condition that the (-20000 and -20999) YES YES
developer determine is abnormal
7/5/12 7/5/12 61
62. PL/SQL
DEFINE p_dept_desc = ‘Information Technology’
DEFINE p_dept_no = 300
SET SERVEROUTPUT ON
DECLARE
e_invalid_department EXCEPTION;
BEGIN
UPDATE departments
SET department_name = ‘&p_dept_desc’
WHERE department_id = &p_dept_no ;
IF SQL%NOTFOUND THEN
RAISE e_invalid_department;
END IF;
COMMIT;
EXCEPTION
WHEN e_invalid_department THEN
DBMS_OUTPUT.PUT_LINE(‘No such department id.’);
END;
7/5/12 7/5/12 62
63. PL/SQL
Reference the standard name in the exception handling routine.
Sample Pre-defined exceptions
NO_DATA_FOUND TOO_MANY_ROWS
INVALID_CURSOR ZERO_DIVIDE
* The following block produces error with the execution part, the error is trapped in
the exception part.
SET SERVEROUTPUT ON
DECLARE
v_deptno NUMBER(4);
v_loc_id NUMBER(4);
BEGIN
SELECT department_id, location_id
INTO v_deptno, v_loc_id
FROM departments;
EXCEPTION
WHEN TOO_MANY_ROWS THEN --traps pre-defined error
DBMS_OUTPUT.PUT_LINE(‘fetches more than one row, use cursor…’);
WHEN OTHERS THEN --traps errors which is not handled by above exception
DBMS_OUTPUT.PUT_LINE(‘this error not trapped by exception..’);
END;
7/5/12 7/5/12 63
64. PL/SQL
PRAGMA (pseudo-instructions) is the keyword that signifies that the statement is a
compiler directive, which is not processed when the PL/SQL block is executed.
PRAGMA EXCEPTION_INIT(exception,oracle_error_number);
Trap for Oracle Server error number -2292, an integrity constraint violation
DEFINE p_deptno = 10
SET SERVEROUTPUT ON
DECLARE
e_emps_remaining EXCEPTION;
PRAGMA EXCEPTION_INIT (e_emps_remaining, -2292);
BEGIN
DELETE FROM departments WHERE department_id = &p_deptno;
COMMIT;
EXCEPTION
WHEN e_emps_remaining THEN --traps non-predefined error
DBMS_OUTPUT.PUT_LINE(‘Cannot remove dept ‘|| TO_CHAR(&p_deptno)
|| ‘. Employees exists. ‘);
END;
7/5/12 7/5/12 64
65. PL/SQL
SQLCODE Returns the numeric value for the error code.
SQLERRM Returns the message associated with the error number.
SET SERVEROUTPUT ON
DECLARE
v_deptno NUMBER(4);
v_loc_id NUMBER(4);
err_num NUMBER;
err_msg VARCHAR2(100);
BEGIN
SELECT department_id, location_id
INTO v_deptno, v_loc_id
FROM departments;
EXCEPTION
WHEN ZERO_DIVIDE THEN --traps pre-defined error
DBMS_OUTPUT.PUT_LINE(‘number is divided by zero…’);
WHEN OTHERS THEN --traps errors with Error Message
err_num := SQLCODE;
err_msg := SUBSTR(SQLERRM,1,100);
DBMS_OUTPUT.PUT_LINE(‘Trapped Error: ‘|| err_msg );
END;
7/5/12 7/5/12 65
66. PL/SQL
Example
DECLARE
.. ..
e_no_rows EXCEPTION;
e_integrity EXCEPTION;
PRAGMA EXCEPTION_INIT(e_integrity, -2292);
BEGIN
FOR c_record IN emp_cursor LOOP
BEGIN
SELECT .. .. ;
Sub-block can handle UPDATE .. .. ; Block without
an exception or pass IF SQL%NOTFOUND THEN the exception.
the exception to the RAISE e_no_rows;
enclosing block. END IF;
END;
END LOOP;
EXCEPTION
WHEN e_integrity THEN .. ..
WHEN e_no_rows THEN .. .. Error Trapped.
END;
7/5/12 7/5/12 66
67. PL/SQL
Summary
Exception Types
Predefined Oracle Server error
Non-predefined Oracle Server error
User-defined error
Exception Trapping
Exception Handling
Trap the exception within the PL/SQL block
Propagate the exception
7/5/12 7/5/12 67
69. PL/SQL
<header> IS | AS
Declaration section
.. ..
BEGIN
.. ..
EXCEPTION
.. ..
A Subprogram : END;
Is a named PL/SQL block that can accept parameters
and be invoked from a calling environment.
Procedure - that performs an action
Function - that computes a value
Provides easy maintenance , improved data security,
improved performance.
7/5/12 7/5/12 69
70. PL/SQL
A procedure is a type of named subprogram that performs an action.
Procedure accepts parameters / arguments for further calls.
A procedure can be stored in the database, as a schema object, for repeated execution.
Procedure
IN parameter (default)
Calling
environment OUT parameter
IN OUT parameter
<header> IS | AS
.. ..
BEGIN
.. ..
EXCEPTION
.. ..
END;
7/5/12 7/5/12 70
71. PL/SQL
CREATE OR REPLACE PROCEDURE raise_salary
(p_id IN employees.employee_id%TYPE)
IS
BEGIN
UPDATE employees
SET salary = salary * 1.20
WHERE employee_id = p_id; 176 p_id
END raise_salary;
/
EXECUTE raise_salary(176); Actual parameters Formal parameters
Formal parameters : Variables declared in the parameter list of a subprogram specification.
CREATE PROCEDURE raise_sal (p_id NUMBER, p_amount NUMBER)
.. ..
END raise_sal;
Actual parameters : Variables or expressions referenced in the parameter list of a
subprogram call.
raise_sal(v_id,200)
7/5/12 7/5/12 71
72. PL/SQL
CREATE OR REPLACE PROCEDURE query_emp
(p_id IN employees.employee_id%TYPE,
p_name OUT employees.last_name%TYPE,
p_sal OUT employees.salary%TYPE)
IS
BEGIN 171 p_id
SELECT last_name, salary
INTO p_name, p_sal
SMITH p_name
FROM employees
WHERE employee_id = p_id;
END query_emp; 7400 p_sal
/
VARIABLE g_name VARCHAR2(20)
VARIABLE g_sal NUMBER
EXECUTE query_emp(171, :g_name, :g_sal)
PRINT g_name g_sal
7/5/12 7/5/12 72
73. PL/SQL
‘8006330575’ ‘(800)633-0575’ p_phone_no
CREATE OR REPLACE PROCEDURE format_phone
(p_phone_no IN OUT VARCHAR2)
IS
BEGIN
p_phone_no := ‘(‘ || SUBSTR(p_phone_no,1,3) ||
‘)’ || SUBSTR(p_phone_no,4,3) ||
‘-’ || SUBSTR(p_phone_no,7) ;
END format_phone;
/
VARIABLE g_ph_no VARCHAR2(15)
BEGIN
:g_ph_no := ‘8006330575’;
END;
/
PRINT g_ph_no
EXECUTE format_phone(:g_ph_no)
PRINT g_ph_no
7/5/12 7/5/12 73
74. PL/SQL
CREATE OR REPLACE PROCEDURE add_dept
(p_name IN departments.department_name%TYPE DEFAULT ‘unknown’,
p_loc IN departments.location_id%TYPE DEFAULT 1700 )
IS
BEGIN
INSERT INTO departments(department_id, department_name,
location_id)
VALUES(dept_seq.NEXTVAL, p_name, p_loc);
END add_dept;
/
Note : OUT and IN OUT parameters are not permitted to have DEFAULT values.
7/5/12 7/5/12 74
76. PL/SQL
DECLARE
v_id NUMBER := 163;
BEGIN
raise_salary(v_id); -- invoke procedure
COMMIT;
END;
7/5/12 7/5/12 76
77. PL/SQL
CREATE OR REPLACE PROCEDURE process_emps
IS
CURSOR emp_cursor IS
SELECT employee_id FROM employees;
BEGIN
FOR emp_rec IN emp_cursor
LOOP
raise_salary(emp_rec.employee_id); -- invoke procedure
END LOOP;
COMMIT;
END process_emps;
/
DROP PROCEDURE raise_sal;
7/5/12 7/5/12 77
78. PL/SQL
CREATE OR REPLACE PROCEDURE leave_emp2
(p_id IN employees.employee_id%TYPE)
IS
PROCEDURE log_exec
IS
BEGIN
INSERT INTO log_table (user_id, log_date)
VALUES (user, sysdate);
END log_exec;
BEGIN
DELETE FROM employees
WHERE employee_id = p_id;
log_exec;
END leave_emp2;
/
7/5/12 7/5/12 78
79. PL/SQL
Called PROCEDURE p2
Called PROCEDURE p2
Procedure IS Procedure IS
.. ..
BEGIN BEGIN
.. ..
-- error -- error
Calling .. Calling ..
Procedure EXCEPTION Procedure EXCEPTION
-- handled -- unhandled
PROCEDURE p1 END p2; PROCEDURE p1 END p2;
IS IS
.. ..
BEGIN BEGIN Control
.. .. returns
P2(arg1); Control P2(arg1); to the
returns exception
.. ..
to the section
EXCEPTION calling EXCEPTION of
.. procedure .. calling
END p1; END p1; procedure
7/5/12 7/5/12 79
80. PL/SQL
Summary
Procedure – performs an action
IN OUT IN OUT
DEFAULT option
Passing Parameters
Invoking Procedure from Anonymous and
another Procedure
Standalone Procedure
Handled / Un-Handled Exception
Removing Procedure
7/5/12 7/5/12 80
82. PL/SQL
A function is a named PL/SQL Block that returns a Value.
A function can be stored in the database as a schema object for
repeated execution.
A function is called as part of an expression. Function
The function must have IN parameter (default)
at least one RETURN clause in the header.
at least one RETURN statement in the executable. FUNCTION
RETURN dataype
Accept only valid SQL data-types, not PL/SQL types IS | AS
.. ..
Return only valid SQL data-types, not PL/SQL types BEGIN
.. RETURN v_s ..
EXCEPTION
.. ..
END;
7/5/12 7/5/12 82
83. PL/SQL
CREATE OR REPLACE FUNCTION get_sal
(p_id IN employees.employee_id%TYPE)
RETURN NUMBER
IS
v_salary employees.salary%TYPE := 0;
BEGIN
SELECT salary
INTO v_salary 117 p_id
FROM employees
WHERE employee_id = p_id; RETURN v_salary
RETURN v_salary;
END get_sal;
/
VARIABLE g_sal NUMBER
EXECUTE :g_sal := get_sal(117)
PRINT g_sal
7/5/12 7/5/12 83
84. PL/SQL
CREATE OR REPLACE FUNCTION tax(p_value IN NUMBER)
RETURN NUMBER IS
BEGIN
RETURN (p_value * 0.08);
END tax;
/
SELECT employee_id, last_name, salary, tax(salary)
FROM employees
WHERE department_id = 60;
SELECT employee_id, tax(salary)
FROM employees
WHERE tax(salary) > (SELECT MAX(tax(salary))
FROM employees
WHERE department_id = 30)
ORDER BY tax(salary) DESC;
7/5/12 7/5/12 84
85. PL/SQL
CREATE OR REPLACE FUNCTION dml_call_sql
(p_sal NUMBER)
RETURN NUMBER
IS
BEGIN
INSERT INTO employees(employee_id, last_name,
email, hire_date, job_id, salary)
VALUES (999, ‘employee1’, ’emp1@cpm.com’,
sysdate, ‘SA_MAN’, 1000);
RETURN (p_sal + 100);
END;
/
UPDATE employees
SET salary = dml_call_sql(2000)
WHERE employee_id = 170;
7/5/12 7/5/12 85
86. PL/SQL
EXECUTE privilege for subprograms
hr.employees SELECT
In-Direct access
GRANT SELECT EXECUTE scott.query_emp
ON employees
TO scott;
Direct access
PROCEDURE
query_emp
GRANT EXECUTE Green
Scott ON query_emp
TO green;
7/5/12 7/5/12 86
88. PL/SQL
USER_OBJECTS Provides general information about the object
USER_SOURCE Provides the text of the object
USER_ERRORS Shows compilation errors
SHOW ERRORS PROCEDURE log_execution
DESCRIBE tax
7/5/12 7/5/12 88
90. PL/SQL
Group logically related PL/SQL types, items and subprograms.
Allow the Oracle Server to read multiple objects into memory at once.
Package Procedure A
SPECIFICATION declaration
Package Procedure B
BODY definition
Procedure A
definition
7/5/12 7/5/12 90
91. PL/SQL
Public Variable
Package
Procedure A
SPECIFICATION Public Procedure
declaration
Private Variable
Procedure B
Package definition Private Procedure
BODY
Procedure A Public procedure
definition
Local Variable
7/5/12 7/5/12 91
92. PL/SQL
CREATE PACKAGE keyword for package specification.
CREATE PACKAGE BODY keyword for package body.
A package specification can exist without a package body,
but the package body cannot exist without a package specification.
Package XYZ Package UVW
7/5/12 7/5/12 92
93. PL/SQL
CREATE OR REPLACE PACKAGE comm_package IS
g_comm NUMBER := 0.10;
PROCEDURE reset_comm (p_comm IN NUMBER);
END comm_package;
CREATE OR REPLACE PACKAGE BODY comm_package IS
FUNCTION validate_comm (p_comm IN NUMBER)
RETURN BOOLEAN IS
v_max_comm NUMBER;
BEGIN
SELECT MAX(commission_pct) INTO v_max_comm FROM employees;
IF p_comm > v_max_comm THEN
RETURN(FALSE);
ELSE
RETURN (TRUE);
END IF;
END validate_comm; Invoke a function
within the
PROCEDURE reset_comm (p_comm IN NUMBER) IS same package
BEGIN
IF validate_comm(p_comm)THEN
g_comm := p_comm --reset the global variable
ELSE RAISE_APPLICATION_ERROR(-20210,’Invalid Commission’);
END IF;
END reset_comm;
END comm_package;
7/5/12 7/5/12 93
94. PL/SQL
Invoke a package procedure from SQL Worksheet
EXECUTE comm_package.rest_comm(0.15)
Invoke a package procedure in a different schema
EXECUTE scott.comm_package.rest_comm(0.15)
Invoke a package procedure in a remote database
EXECUTE scott.comm_package.rest_comm@db1(0.15)
7/5/12 7/5/12 94
95. PL/SQL
CREATE OR REPLACE PACKAGE global_consts IS
mile_2_kilo CONSTANT NUMBER := 1.6093;
kilo_2_mile CONSTANT NUMBER := 0.6214;
yard_2_meter CONSTANT NUMBER := 0.9144;
meter_2_yard CONSTANT NUMBER := 1.0936;
END global_consts;
/
EXECUTE DBMS_OUTPUT.PUT_LINE(’20 miles = ‘ ||
20 * global_consts.mile_2_kilo|| ‘ km’)
CREATE OR REPLACE PROCEDURE me_to_yard
( p_meter IN NUMBER,
p_yard OUT NUMBER)
IS
BEGIN
p_yard := p_meter * global_consts.meter_2_yard;
END me_to_yard;
/
VARIABLE yard NUMBER
EXECUTE me_to_yard (1, :yard)
PRINT yard
7/5/12 7/5/12 95
96. PL/SQL
Enables you to use the same name for different subprograms inside a
PL/SQL block, a subprogram, or a package
Requires the formal parameters of the subprograms to differ in number,
order, or data type family.
CREATE OR REPLACE PACKAGE over_pack IS
PROCEDURE add_dept
(p_deptno IN departments.department_id%TYPE,
p_name IN departments.department_name%TYPE DEFAULT ‘unknown’,
p_loc IN departments.location_id%TYPE DEFAULT 0);
PROCEDURE add_dept
(p_dno IN dept.dno%TYPE DEFAULT 0,
p_dname IN dept.dname%TYPE DEFAULT ‘unknown’);
PROCEDURE add_dept
(p_dname IN col_dept.dname%TYPE DEFAULT ‘unknown’,
p_hod IN col_dept.hod%TYPE DEFAULT ‘unknown’);
END over_pack;
/
7/5/12 7/5/12 96
97. PL/SQL
CREATE OR REPLACE PACKAGE BODY over_pack IS
PROCEDURE add_dept
(p_deptno IN departments.department_id%TYPE,
p_name IN departments.department_name%TYPE DEFAULT ‘unknown’,
p_loc IN departments.location_id%TYPE DEFAULT 0)
IS
BEGIN
INSERT INTO departments(department_id, department_name, location_id)
VALUES (p_deptno, p_name, p_loc);
END add_dept;
PROCEDURE add_dept
(p_dno IN dept.dno%TYPE DEFAULT 0 ,
p_dname IN dept.dname%TYPE DEFAULT ‘unknown’)
IS
BEGIN
INSERT INTO dept(dno, dname) VALUES (p_dno, p_dname);
END add_dept;
PROCEDURE add_dept
(p_dname IN college_dept.dname%TYPE DEFAULT ‘unknown’,
p_hod IN college_dept.hod%TYPE DEFAULT ‘unknown’)
IS
BEGIN
INSERT INTO college_dept(dname, hod) VALUES (p_dname, p_hod);
END add_dept;
END over_pack;
EXECUTE over_pack.add_dept(980 , ‘Education’, 2500)
EXECUTE over_pack.add_dept(90 , ‘Training’)
EXECUTE over_pack.add_dept(‘Database’, ‘DeCarl’)
7/5/12 7/5/12 97
98. PL/SQL
CREATE OR REPLACE PACKAGE taxes_pack
IS
FUNCTION tax(p_value IN NUMBER)
RETURN NUMBER;
END taxes_pack;
/
CREATE OR REPLACE PACKAGE BODY taxes_pack
IS
FUNCTION tax(p_value IN NUMBER)
RETURN NUMBER
IS
v_rate NUMBER := 0.08;
BEGIN
RETURN (p_value * v_rate);
END tax;
END taxes_pack;
/
SELECT last_name, salary, taxes_pack.tax(salary)
FROM employees;
7/5/12 7/5/12 98
99. PL/SQL
Better Performance
The entire package is loaded into memory when the package is first referenced.
There is only one copy in memory for all users.
The dependency hierarchy is simplified.
Over-loading : Multiple subprograms of the same name.
DROP PACKAGE package_name;
DROP PACKAGE BODY package_name;
7/5/12 7/5/12 99
100. PL/SQL
Summary
Package SPECIFICATION
Package BODY
Invoking Package – EXECUTE
Bodiless Package
Overloading
User Defined Package
7/5/12 7/5/12 100
102. PL/SQL
Are provided with the Oracle server.
Extend the functionality of the database.
Parse
Check for the statement syntax
Ensure the referenced object exist
Ensure the relevant privilege to those object.
Bind
Join the fetched value to the variable / column / column alias
Execute
All necessary information and resources are met
Fetch (only SELECT)
Rows requested are selected and ordered.
7/5/12 7/5/12 102
103. PL/SQL
Use OPEN_CURSOR to establish an area memory to process a SQL statement.
Use PARSE to establish the validity of the SQL statement.
Use EXECUTE function to run the SQL statement. The function returns the number
of row processed.
Use CLOSE_CURSOR to close the cursor.
CREATE OR REPLACE PROCEDURE delete_all_rows
(p_tab_name IN VARCHAR2, p_rows_del OUT NUMBER)
IS
cursor_name INTEGER;
BEGIN
cursor_name := DBMS_SQL.OPEN_CURSOR;
DBMS_SQL.PARSE(cursor_name, ‘DELETE FROM ‘ || p_tab_name,
DBMS_SQL.NATIVE);
p_rows_del := DBMS_SQL.EXECUTE (cursor_name);
DBMS_SQL.CLOSE_CURSOR(cursor_name);
END;
/
VARIABLE deleted NUMBER
EXECUTE delete_all_rows(‘employees’, :deleted)
PRINT deleted
7/5/12 7/5/12 103
104. PL/SQL
CREATE OR REPLACE PROCEDURE del_rows
(p_table_name IN VARCHAR2,
p_rows_deld OUT NUMBER)
IS
BEGIN
EXECUTE IMMEDIATE ‘delete from ‘ || p_table_name;
p_rows_deld := SQL%ROWCOUNT;
END;
/
VARIABLE deleted NUMBER
EXECUTE del_rows(‘test_employees’, :deleted)
PRINT deleted
7/5/12 7/5/12 104
105. PL/SQL
Summary
Oracle Supplied Packages
Are provided with the Oracle server.
Extend the functionality of the database.
7/5/12 7/5/12 105
107. PL/SQL
Used to store large unstructured data such as text,
graphic, images, films and sound waveforms
Stores locator to the LOB’s value
CLOB
BLOB BFILE
7/5/12 7/5/12 107
108. PL/SQL
ALTER TABLE employees ADD emp_video BFILE;
CREATE OR REPLACE DIRECTORY log_files AS ‘c:pict’;
GRANT READ ON DIRECTORY log_files TO PUBLIC;
CREATE OR REPLACE PROCEDURE load_emp_bfile
(p_file_loc IN VARCHAR2) IS
v_file BFILE;
v_filename VARCHAR2(16);
CURSOR emp_cursor IS
SELECT first_name FROM employees
WHERE department_id = 60 FOR UPDATE;
BEGIN
FOR emp_record IN emp_cursor LOOP
v_filename := emp_record.first_name || ‘.bmp’;
v_file := BFILENAME(p_file_loc, v_filename);
DBMS_LOB.FILEOPEN(v_file);
UPDATE employees SET emp_video = v_file
WHERE CURRENT OF emp_cursor;
DBMS_OUTPUT.PUT_LINE(‘LOADED FILE: ‘||v_filename||‘Size:‘
|| DBMS_LOB.GETLENGTH(v_file));
DBMS_LOB.FILECLOSE(v_file);
END LOOP;
END load_emp_bfile; EXECUTE load_emp_bfile(‘LOG_FILES’)
7/5/12 7/5/12 108
110. PL/SQL
Is a PL/SQL block or a PL/SQL procedure associated with a table,
view, schema, or the database.
Executes implicitly whenever a particular event takes place.
Two types of Triggers
Application Trigger
Fires whenever an event occurs with a particular application.
Database Trigger
Fires whenever a data event (such as DML) or system event
(such as logon or shutdown on a schema or database)
7/5/12 7/5/12 110
111. PL/SQL
BEFORE Execute the trigger body before the
triggering DML event on a table.
AFTER Execute the trigger body after the triggering
DML event on a Table
INSTEAD OF Used for views.
7/5/12 7/5/12 111
112. PL/SQL
DML statement
INSERT INTO departments (department_id,department_name, location_id)
VALUES (400, ‘COUNSULTING’, 2400);
BEFORE statement trigger
Triggering BEFORE row trigger
action AFTER row trigger
AFTER statement trigger
UPDATE employees SET salary = salary * 1.5 WHERE department_id = 30;
BEFORE statement trigger
30
30 BEFORE row trigger
Triggering 30 AFTER row trigger
30 ... ...
action 30 BEFORE row trigger
30 AFTER row trigger
AFTER statement trigger
7/5/12 7/5/12 112
113. PL/SQL
Create a trigger to restrict inserts into the EMPLOYEES table to certain
business hours, i.e. 8.00 am to 6.00 pm, Monday through Friday.
CREATE OR REPLACE TRIGGER secure_emp
BEFORE INSERT ON employees
BEGIN
IF (TO_CHAR(SYSDATE,’DY’) IN (‘SAT’,’SUN’)
OR
TO_CHAR(SYSDATE,’HH24:MI’) NOT BETWEEN
’08:00’ AND ’18:00’) THEN
RAISE_APPLICATION_ERROR(-20500,’You many insert
into Employees table only during business
hours.’);
END IF;
END secure_emp;
7/5/12 7/5/12 113
114. PL/SQL
Combine several triggering events into one trigger body.
CREATE OR REPLACE TRIGGER secure_emp1
BEFORE INSERT OR UPDATE OR DELETE ON employees
BEGIN
IF (TO_CHAR(SYSDATE,’DY’) IN (‘SAT’,’SUN’) OR
TO_CHAR(SYSDATE,’HH24:MI’) NOT BETWEEN ‘08:00’ AND ’18:00’) THEN
IF DELETING THEN
RAISE_APPLICATION_ERROR(-20502,’Delete during office hours...’);
ELSIF INSERTING THEN
RAISE_APPLICATION_ERROR(-20503,’Insert during office hours...’);
ELSIF UPDATING(‘SALARY’) THEN
RAISE_APPLICATION_ERROR(-20504,’Update SALARY during office hours’);
ELSE
RAISE_APPLICATION_ERROR(-20506,’Update during office hours’);
END IF;
END IF;
END;
7/5/12 7/5/12 114
115. PL/SQL
Data Operation : OLD Value : NEW Value
INSERT NULL Inserted value
UPDATE Value before update Value after update
DELETE Value before delete NULL
Create a trigger to allow job id other than AD_PRES , VD_VP cannot earn
more than 15000
CREATE OR REPLACE TRIGGER restrict_salary
BEFORE INSERT OR UPDATE OF salary ON employees
FOR EACH ROW
BEGIN
IF NOT (:NEW.job_id IN (‘AD_PRES’, ‘AD_VP’)) AND
:NEW.salary > 15000 THEN
RAISE_APPLICATION_ERROR(-20202,’Employees cannot earn
more than this amount’);
END IF;
END;
/
7/5/12 7/5/12 115
116. PL/SQL
Only Available for ROW Triggers
CREATE OR REPLACE TRIGGER audit_emp_values
AFTER DELETE OR INSERT OR UPDATE ON employees
FOR EACH ROW
BEGIN
INSERT INTO aud_emp(user_name, timestampid, old_lname,
new_lname, old_title, new_title,
old_salary, new_salary)
VALUES (USER, SYSDATE, :OLD.employee_id, :OLD.last_name,
:NEW.last_name, :OLD.job_id, :NEW.job_id,
:OLD.salary, :NEW.salary);
END;
/
SELECT * FROM aud_emp;
7/5/12 7/5/12 116
117. PL/SQL
To restrict the trigger action for those rows satisfy a certain condition,
provide WHEN clause.
CREATE OR REPLACE TRIGGER derive_commpct
BEFORE INSERT OR UPDATE OF salary ON employees
FOR EACH ROW
WHEN (NEW.job_id = ‘SA_REP’)
BEGIN
IF INSERTING THEN
:NEW.commission_pct := 0;
ELSIF :OLD.commission_pct IS NULL THEN
:NEW.commission_pct := 0;
ELSE
:NEW.commission_pct := OLD.commission_pct + 0.05;
END IF;
END;
/
7/5/12 7/5/12 117
118. PL/SQL
TRIGGERS PROCEDURES
Source Code USER_TRIGGERS Source Code USER_SOURCE
Implicitly Invoked Explicitly Invoked
COMMIT, SAVEPOINT, ROLLBACK COMMIT, SAVEPOINT,
are not allowed ROLLBACK are allowed
ALTER TRIGGER trigger_name DISABLE|ENABLE;
ALTER TABLE table_name DISABLE|ENABLE ALL TRIGGERS;
DROP TRIGGER trigger_name;
7/5/12 7/5/12 118
119. PL/SQL
CREATE, ALTER or DROP
Logging ON / OFF
Shutting down or starting up the database.
CREATE OR REPLACE TRIGGER logon_trig
AFTER LOGON ON SCHEMA | DATABASE
BEGIN
INSERT INTO log_trig_table(user_id, log_date, action)
VALUES (USER, SYSDATE, ‘Logging on’);
END logon_trig;
/
CREATE OR REPLACE TRIGGER logoff_trig
BEFORE LOGOFF ON SCHEMA | DATABASE
BEGIN
INSERT INTO log_trig_table(user_id, log_date, action)
VALUES (USER, SYSDATE, ‘Logging Off’);
END logoff_trig;
/
7/5/12 7/5/12 119
120. PL/SQL
CREATE OR REPLACE TRIGGER check_salary
BEFORE UPDATE OF salary ON EMPLOYEES
FOR EACH ROW
WHEN (NEW.salary < OLD.salary)
BEGIN
RAISE_APPLICATION_ERROR(-20509,
‘Do not decrease salary..’);
END check_salary;
/
CREATE OR REPLACE TRIGGER log_emp
BEFORE INSERT ON EMPLOYEES
CALL log_execution;
END log_emp;
/
7/5/12 7/5/12 120
123. PL/SQL
Procedure View or Table
Procedure
Direct Direct
dependency dependency
Referenced
Dependent
Indirect
Dependent dependency Referenced
7/5/12 7/5/12 123
124. PL/SQL
utldtree.sql
Direct Local Dependency
Procedure Procedure View Table
Procedure Procedure View Table
Definition
changed
INVALID INVALID INVALID
SELECT name, type, referenced_name, referenced_type
FROM user_dependencies
WHERE referenced_name IN (‘EMPLOYEES’,’EMP_VW’);
EXECUTE deptree_fill(‘TABLE’,’HR’,’EMPLOYEES’); ideptree
SELECT nested_level, type, name FROM deptree Indirect
ORDER BY seq#; dependency
7/5/12 7/5/12 124
125. PL/SQL
ALTER PROCEDURE proc_name COMPILE;
ALTER FUNCTION func_name COMPILE;
ALTER PACKAGE pack_name COMPILE [PACKAGE];
ALTER PACKAGE pack_name COMPILE BODY;
ALTER TRIGGER trig_name COMPILE;
7/5/12 7/5/12 125
