Trigger:When Case is generated then send Mail to Relevant Contact Email

trigger SendEmailTOCustomer on Case (after insert) {
    string e;
    if(Trigger.IsInsert){
      for(case b:trigger.new){
      ID d=b.contactid;
      contact con=[select name,email from contact where id=:d];
      system.debug('3333333333333333333333333'+con.email);
      e=con.email;
       Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
               String[] toAddresses = new String[] {e};
               mail.setToAddresses(toAddresses);
               mail.setSubject('New Record Is Inserted');
               mail.setBccSender(false);
               mail.setUseSignature(false);
               mail.setPlainTextBody('hi padam');
               Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });
      }
    }  
}

Sosl Example programme for visualforce page

============VFPAGE======================
<apex:page controller="soslexampleclass">
  <apex:form >
  <apex:pageBlock >
    <apex:inputText value="{!str}"/>
    <apex:commandButton value="Show Records" action="{!showRecordsMethod}"/>
    </apex:pageBlock>
  </apex:form>
  <apex:pageBlock title="accounts">
    <apex:pageBlockTable value="{!acclist}" var="acc">
       <apex:column value="{!acc.name}"/>
    </apex:pageBlockTable>
  </apex:pageBlock>
  <apex:pageBlock title="conatcs">
    <apex:pageBlockTable value="{!conlist}" var="acc">
       <apex:column value="{!acc.name}"/>
       <apex:column value="{!acc.email}"/>
       </apex:pageBlockTable>
  </apex:pageBlock>
  <apex:pageBlock title="opportunities">
    <apex:pageBlockTable value="{!opplist}" var="acc">
       <apex:column value="{!acc.name}"/>
       <apex:column value="{!acc.stagename}"/>
       </apex:pageBlockTable>
       <apex:pageBlock title="leads">
    <apex:pageBlockTable value="{!leadlist}" var="acc">
       <apex:column value="{!acc.name}"/>
       <apex:column value="{!acc.company}"/>
       </apex:pageBlockTable>
  </apex:pageBlock>
 
  </apex:pageBlock>
 
  </apex:page>


================CONTROLLER===================
public class soslexampleclass {

    public String str { get; set; }
    public List<lead> leadlist{set;get;}
    public List<Account> acclist{set;get;}
    public List<Contact> conlist{set;get;}
    public List<opportunity> opplist{set;get;}
    public void showRecordsMethod() {
        system.debug('444444444444444444444'+str);
        leadlist= new List<lead>();
        acclist=new list<account>();
        conlist=new list<contact>();
        opplist=new list<opportunity>();
        List<List<SObject>> searchlist=[find :str IN ALL FIELDS RETURNING ACCOUNT(ID,NAME),CONTACT(NAME,EMAIL),OPPORTUNITY(NAME,STAGENAME),LEAD(COMPANY,NAME,STATUS)];
        acclist=((List<account>)searchlist[0]);
        conlist=((List<contact>)searchlist[1]);
        opplist=((List<opportunity>)searchlist[2]);
        leadlist=((List<lead>)searchlist[3]);
    }

}

Trigger:When child Record is Inserted and Relevant parent Record is updated

trigger afterinsertrecord on ObjectB__c (after insert,after update) {
    for(ObjectB__c objB:trigger.new){
    system.debug('333333333333333333333333333333333333333333333333333'+objB);
       for(ObjectA__c objA:[select id,name, number__c from  ObjectA__c ]){
       system.debug('33333333333333333333333333366666666666666666666666666666666666666666666'+objA);
        if(objB.objectA__c==objA.id){
           objA.number__c=objA.number__c+objB.number__c;
           update objA;
        }    }}
}