APEX TRIGGERS EXAMPLES

Apex triggers scenarios:

Scenario 1 : when ever a record is inserted to the account automatically the same record will also insert in contact?

Answer : 

trigger scenario1 on Account (after insert) 
{
    List<contact> con = new list<contact>();
    for(account acc:trigger.new)
    {   
        contact c = new contact();
        c.lastname = acc.name;
        con.add(c);   
    }
    insert con;
}

Scenario 2 : how to create a trigger to show user an error message when  Limit reached to create new records?


Answer :

trigger scenario2 on Account (before insert, befor update) 
{
    list<account> a = [select id,name from account where createdate=today or lastmodifieddate=today]
    for(account acc : trigger.new)
    {
        count= a.size();
        if(count>2)
        {
            acc.adderror('reached limit today');
        }        
    }

}


Scenario 3 : can not delete insert and update the record for a particular user using trigger?

Answer :

trigger scenario3 on Account (before delete,before insert, before update) 
{
   user u = [select id,name from user where username = 'swethag7890@gmail.com'];
    if(u.id == userinfo.getuserid())
    {
        if(trigger.isdelete)
        {
        for(account a: trigger.old)
        {
            a.adderror('cant delete record');
        }
        }
        if(trigger.isinsert)
        {
        for(account b: trigger.new)
        {
            b.adderror('cant insert record');
        }
        }
         if(trigger.isupdate)
        {
        for(account c: trigger.new)
        {
            c.adderror('cant update record');
        }
        }
    }

}