29-10-2013(plsql functions,packages,triggers).docx

8/14/2019 29-10-2013(plsql functions,packages,triggers).docx

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===================================================================================

================================================

PLSQL FUNCTION

===================================================================================

================================================

PLSQL FUNCTION TO DISPALY THE CURRENT DATE

create or replace function today

return date is

vday date; --local variable

begin

select sysdate into vday from dual;

return vday; --return the value for vday

end;

/

--EXECUTION 1

select today from dual;

--EXECUTION 2

begin

dbms_output.put_line('Today is:'||today);

end;

======================================================================


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WRITE A PLSQL FUNCTION TO INCREMENT THE SALARY BY 10% FOR ALL EMPLOYEES

OF DEPARTMENT 40

create or replace function salary1

return number is --(return datatype)

sal number; --(variablename date)

begin

select salary into sal from employees where department_id=40;

return(sal*1.1);

end;

/

begin

dbms_output.put_line('new salary is:='||salary1);

end;

=====================================================================

WRITE A PLSQL FUNCTION TO ACCEPT AN EMPLOYEE CODE AND RETURN THE TOTAL

SALARY(SALARY+COMMISSION) OF THE EMOLOYEE. IN CASE THE COMMISSION IS NULL

THEN THROW THE EXCEPTION NO_COMMISSION.

create or replace function get_totalsalary(empid IN employees.employee_id%type)

return number IS

sal number;

com number;


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--custom exception is declared

no_commission exception;

begin

--write business logic

--if commission is null

--exception raised

select salary,commission_pct into sal,com from employees where employee_id=&emp_id;

if com is null then

RAISE no_commission;

end if;

return(sal+com);

exception

--exception handled

when no_commission then

raise_application_error(-20401,'commission not found');

end;

begin

dbms_output.put_line('total salary='||get_totalsalary(&empid));

end;

===================================================================================

=================================================

STORED PACKAGES


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===================================================================================

=================================================

A package is a database object which encapsulate realted procedure, functions, associated cursors

and variables together as logical unit in the database.

create or replace package emp_operations

is

procedure hire_employee;

procedure fire_employee(empid virtusa_employees.employee_id%type);

function get_totalsalary(empid employees.employee_id%type) return number;

end;

-----------------------------------------------------------------------------------

--------------

create or replace package body emp_operations

is

procedure hire_employee is

begin

insert into virtusa_employees(employee_id,first_name,last_name,project_id)

values(904,'neerav','thacker',805);

end hire_employee;

procedure fire_employee(empid virtusa_employees.employee_id%type)

is

begin

delete from virtusa_employees where employee_id=empid;

exception


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when no_data_found then

raise_application_error(-20409,'Employee doesnot exist!');

end fire_employee;

function get_totalsalary(empid employees.employee_id%type) return number IS

sal number;

com number;

no_commission exception;

begin

select salary,commission_pct into sal,com from employees where employee_id=empid;

if com is null then

RAISE no_commission;

end if;

return(sal+com);

exception

when no_commission then

raise_application_error(-20401,'commission not found');

end get_totalsalary;

end;

--exceution

select emp_operations.get_totalsalary(&empid) from employees;


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===================================================================================

================================

WRITE A PACKAGED PROCEDURE TO UPDATE THE COMMISSION OF THOSE EMPLOYEES

WHO DONOT HAVE COMMISSION .

IF SALARY < 10K,COMMISSION % IS 25%

IF SALARY 25K, COMMISION IS 12%

create or replace package salary_operations

as

procedure salary_increment;

end;

create or replace package body salary_operations

is

procedure salary_increment is

cursor salary_list

is

select * from employees where commission_pct is null;

emp employees%rowtype;

begin

for emp in salary_list

loop


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if emp.salary


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create or replace package salary_sal40

as

procedure increment_s40;

end;

create or replace package body salary_sal40

is

procedure increment_s40 is

cursor salary_list

is

select * from employees where department_id=40;

emp employees%rowtype;

begin

for emp in salary_list

loop

update employees

set salary=salary+(0.1*salary);

end loop;

end increment_s40;

end;

/

begin


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dbms_output.put_line('new salary is:='||emp.salary);

end;

===================================================================================

==========================================

TRIGGERS

===================================================================================

==========================================

What is a Trigger?

A trigger is a pl/sql block structure which is fired when a DML statements like Insert, Delete,

Update is executed on a database table. A trigger is triggered automatically when an associated

DML statement is executed.

Syntax of Triggers

Syntax for Creating a Trigger:

CREATE [OR REPLACE ] TRIGGER trigger_name

{BEFORE | AFTER | INSTEAD OF }

{INSERT [OR] | UPDATE [OR] | DELETE} update[of[some specific fields]]


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[OF col_name]

ON table_name

[REFERENCING OLD AS o NEW AS n]

[FOR EACH ROW]

WHEN (condition)

BEGIN

--- sql statements

END;

1. CREATE [OR REPLACE ] TRIGGER trigger_name - This clause creates a trigger with the given

name or overwrites an existing trigger with the same name.

2. {BEFORE | AFTER | INSTEAD OF } - This clause indicates at what time should the trigger getfired. i.e for example: before or after updating a table. INSTEAD OF is used to create a trigger on a

view. before and after cannot be used to create a trigger on a view.

3. {INSERT [OR] | UPDATE [OR] | DELETE} - This clause determines the triggering event. More

than one triggering events can be used together separated by OR keyword. The trigger gets fired at


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all the specified triggering event.

4. [OF col_name] - This clause is used with update triggers. This clause is used when you want to

trigger an event only when a specific column is updated.

5. CREATE [OR REPLACE ] TRIGGER trigger_name - This clause creates a trigger with the given

name or overwrites an existing trigger with the same name.

6. [ON table_name] - This clause identifies the name of the table or view to which the trigger is

associated.

7. [REFERENCING OLD AS o NEW AS n] - This clause is used to reference the old and new

values of the data being changed. By default, you reference the values as :old.column_name

or :new.column_name. The reference names can also be changed from old (or new) to any other

user-defined name. You cannot reference old values when inserting a record, or new values when

deleting a record, because they do not exist.

8. [FOR EACH ROW] - This clause is used to determine whether a trigger must fire when each row

gets affected ( i.e. a Row Level Trigger) or just once when the entire sql statement is

executed(i.e.statement level Trigger).

9. WHEN (condition) - This clause is valid only for row level triggers. The trigger is fired only for

rows that satisfy the condition specified.

--------------------------

For Example: The price of a product changes constantly. It is important to maintain the history of

the prices of the products.

We can create a trigger to update the 'product_price_history' table when the price of the product is

updated in the 'product' table.


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1) Create the 'product' table and 'product_price_history' table

CREATE TABLE product_price_history

(product_id number(5),

product_name varchar2(32),

supplier_name varchar2(32),

unit_price number(7,2) );

CREATE TABLE product

(product_id number(5),

product_name varchar2(32),

supplier_name varchar2(32),

unit_price number(7,2) );


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2) Create the price_history_trigger and execute it.

CREATE or REPLACE TRIGGER price_history_trigger

BEFORE UPDATE OF unit_price

ON product

FOR EACH ROW

BEGIN

INSERT INTO product_price_history

VALUES

(:old.product_id,

:old.product_name,

:old.supplier_name,

:old.unit_price);


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END;

/

3) Lets update the price of a product.

UPDATE PRODUCT SET unit_price = 800 WHERE product_id = 100

Once the above update query is executed, the trigger fires and updates the

'product_price_history' table.

4)If you ROLLBACK the transaction before committing to the database, the data inserted to

the table is also rolled back.

-----------------------------------------------------------------------------------

-------------------------------------------

create table temp_employee as select * from employees;

CREATE TABLE Emp_log8888

(

Emp_id NUMBER,

Log_date DATE,

New_salary NUMBER,

Action VARCHAR2(20)

);

CREATE TABLE DILEEP AS SELECT * FROM EMPLOYEES;


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SELECT * FROM DILEEP;

CREATE OR REPLACE TRIGGER Log_salary_increase12

AFTER UPDATE ON temp_employee

FOR EACH ROW

WHEN (NEW.Salary > 1000)

BEGIN

INSERT INTO Emp_log8888(Emp_id, Log_date, New_salary, Action) VALUES (:NEW.Employee_id,

SYSDATE, :NEW.salary, 'UPDATED SALARY');

END;

update temp_employee

set salary=salary+1000.0

where department_id=20;

create or replace trigger change_comm

after insert or delete or update of commission_pct on temp_employees

for each row

when(new.commission_pct>1000)

begin

insert into emp_log8888(Emp_id, Log_date, New_salary, Action) values(:NEW.Employee_id,

SYSDATE, :NEW.commission_pct, 'new commission');

end;


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update temp_employees

set commission_pct=commission_pct+1000 where department_id=&deptid;

-----------------------------------------------------------------------------------

-------

--create table and audit table

CREATE TABLE myTable (Name VARCHAR(50) PRIMARY KEY, PhoneNo VARCHAR(15));

CREATE TABLE myTableAudit

(

Operation VARCHAR(10),

RecordedOn DATE DEFAULT SysDate,

OldName VARCHAR(50),

NewName VARCHAR(50),

OldPhone VARCHAR(15),

NewPhone VARCHAR(15)

);


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CREATE OR REPLACE TRIGGER myTableAuditTrigger

AFTER INSERT OR DELETE OR UPDATE ON myTable

FOR EACH ROW

BEGIN

IF INSERTING THEN

INSERT INTO myTableAudit (Operation, NewName, NewPhone)VALUES ('Insert

', :NEW.Name, :NEW.PhoneNo);

end if;

IF DELETING THEN

INSERT INTO myTableAudit (Operation, OldName, OldPhone)VALUES ('Delete', :OLD.Name, :OLD.PhoneNo);

end if;

if UPDATING THEN

INSERT INTO myTableAudit (Operation, OldName, OldPhone, NewName, NewPhone)VALUES

('Update ', :OLD.Name, :OLD.PhoneNo, :NEW.Name, :NEW.PhoneNo);

END IF;

END;

insert into mytable values('DILEEP',9030614858);


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29-10-2013(plsql functions,packages,triggers).docx