Sample Trigger

SET SERVEROUTPUT ON

CREATE OR REPLACE TRIGGER ASDF
BEFORE INSERT OR DELETE OR UPDATE ON SEMP
FOR EACH ROW
BEGIN
 IF UPDATING THEN
  DBMS_OUTPUT.PUT_LINE('NOW ,YOU ARE GOING TO UPDATE ROW INTO TABLE SEMP');
 
 ELSIF INSERTING THEN
  DBMS_OUTPUT.PUT_LINE('NOW,YOU ARE GOING TO INSERT ROW INTO A TABLE SEMP');
 ELSIF DELETING THEN
  DBMS_OUTPUT.PUT_LINE('NOW,YOU ARE GOING TO DELETE ROW FROM TABLE SEMP');

 END IF;

END;
/ 

SHOW ERROR

Sample Proc:

create proc sp_selectinsertupdatedelete
@flag int,
@first varchar(50),
@last varchar(50),
@email varchar(50),
@userid varchar(50),
@pass varchar(100)
as
begin

if (@flag = 1)
begin
select * from anu where userid = @userid
end
if (@flag = 2)
begin
insert into anu values (@first,@last,@email,@userid,@pass)
end
if (@flag=3)
begin
update anu set first=@first,last = @last,email=@email,pass=@pass where userid = @userid
end
if (@flag=4)
begin
delete from anu where userid = @userid
end
end

Different between list.add and list.set

1.List .add:  it insert an element in the list on specified index
2.List .set:  it overrides/replaces an element in the list on specified index

/***********List.add****************/
List<String> lstString=new List<String>{'A','B','C','D'};

System.debug('List elements='+lstString.add(2,'F'));
O/P= List elements={'A','B','F','C','D'}
/***********************************/

/***********List.set****************/
List<String> lstString=new List<String>{'A','B','C','D'};

System.debug('List elements='+lstString.set(2,'F'));
O/P= List elements={'A','B','F','D'}
/***********************************/