Contact DeDupe Trigger

//Trigger to prevent duplicate contacts. Matches based on Email.


trigger contactDeDuplicationTrigger on Contact (before insert, before update) {

//Map to store email and contact details
Map> emailConMap = new Map>();

//Your dynamic query
String contactDynamicQuery = 'select Id,Name,Email from Contact' ;

//Typecasting it to map
Map mapCon = new Map((List)Database.query(contactDynamicQuery));

//Looping the map keys to prepare a map for Email and Contact object

for(Id id:mapCon.keySet())
{
    if(emailConMap.get(mapCon.get(id).Email)!=null)
    emailConMap.get(mapCon.get(id).Email).put(Id,mapCon.get(id));
    else
    emailConMap.put(mapCon.get(id).Email, new Map{Id => mapCon.get(id)}); 
}

//Processing records
for(Contact con:trigger.new)
{
    Map tempMap = new Map();
    
    if(emailConMap.get(con.Email)!=null && !emailConMap.get(con.Email).containsKey(con.Id))
    {
        tempMap = emailConMap.get(con.Email);
        String temp = 'Duplicates found:';
        for(Id id:tempMap.keySet())
        temp+=tempMap.get(id).Name+'('+id+'), ';
        
        //Removing last comma
        temp = temp.substring(0,temp.length()-2);
        
        //Adding error to the record
        con.addError(temp);
    }
}
}

Account DeDupe Trigger

//Trigger to prevent duplicate accounts. Matches records based on Account Name and Account Number

trigger accountDeDuplicationTrigger on Account(before insert, before update) {

//Map to store account name and account details
Map> accNameMap = new Map>();

//Map to store account number and account details
Map> accNumMap = new Map>();

//Your dynamic query
String accountDynamicQuery = 'select Id,Name,AccountNumber from Account' ;

//Typecasting it to map
Map mapAcc = new Map((List)Database.query(accountDynamicQuery));

//Looping the map keys to prepare a map for Account Name and Account Number

for(Id id:mapAcc.keySet())
{
    if(accNameMap.get(mapAcc.get(id).Name)!=null)
    accNameMap.get(mapAcc.get(id).Name).put(Id,mapAcc.get(id));
    else
    accNameMap.put(mapAcc.get(id).Name, new Map{Id => mapAcc.get(id)}); 
    
    if(accNumMap.get(mapAcc.get(id).AccountNumber)!=null)
    accNumMap.get(mapAcc.get(id).AccountNumber).put(Id,mapAcc.get(id));
    else
    accNumMap.put(mapAcc.get(id).AccountNumber, new Map{Id => mapAcc.get(id)}); 

}

//Processing records
for(Account acc:trigger.new)
{
    Map tempMap = new Map();
    
    if((accNameMap.get(acc.Name)!=null && !accNameMap.get(acc.Name).containsKey(acc.Id)) || (accNumMap.get(acc.AccountNumber)!=null && !accNumMap.get(acc.AccountNumber).containsKey(acc.Id)))
    {
        String temp = '';
        
        if(accNameMap.get(acc.Name)!=null && !accNameMap.get(acc.Name).containsKey(acc.Id))
        {
            tempMap = accNameMap.get(acc.Name);
            temp = 'Duplicate Account Name(s) found:';
            for(Id id:tempMap.keySet())
            temp+=tempMap.get(id).Name+'('+id+'), ';
        }
        
        else if(accNumMap.get(acc.AccountNumber)!=null && !accNumMap.get(acc.AccountNumber).containsKey(acc.Id))
        {
            tempMap = accNumMap.get(acc.AccountNumber);
            temp = 'Duplicate Account Number(s) found:';
            for(Id id:tempMap.keySet())
            temp+=tempMap.get(id).Name+' - '+tempMap.get(id).AccountNumber+'('+id+'), ';
        }
        
        //Removing last comma
        temp = temp.substring(0,temp.length()-2);
        
        //Adding error to the record
        acc.addError(temp);
    }
}
}

Schedulable Duplicate contact finder and email notification

// Comment

//Scheduled class for checking duplicate contacts and send an email with the duplicate emails.
//Code can be resued by changing the SOQL and search criteria

global class duplicateContactCheck Implements Schedulable
            {
            //String to store the html email content
            public String htmlOutput{get;set;}
            
                       global void execute(SchedulableContext sc)
                        {
                                    htmlOutput='';
                                    duplicateContactMerger();
                                   
                        }
                        
                        //Method to check for duplicate contacts based on email.
                        //Sending all the duplicate email address to predefined email address
                        public void duplicateContactMerger()
                        {
                                    AggregateResult[] groupedResults = [SELECT Count(Id),Email FROM Contact GROUP BY Email HAVING COUNT(Id)>1];
                                    system.debug('size--'+groupedResults.size());
                                    htmlOutput='
Multiple contacts found for the following email addresses:
';
                                    for(AggregateResult ar:groupedResults)
                                    {
                                    htmlOutput = htmlOutput+ar.get('Email')+'
'; 
                                    } 
                                  htmlOutput=htmlOutput+'';
                                  
                                  //Sending email only when duplicates are found.
                                  if(groupedResults.size()>0)
                                   sendmail();
                        }
                        
                        //Method to send email
                        public void sendmail()
                        {
                                    Messaging.SingleEmailMessage email = new Messaging.SingleEmailMessage();
                                    
                                    //Hard coded email can be replaced with Custom Setting also
                                    string [] toaddress= New string[]{'test@test.com'};
                                    email.setSubject('Duplicate contacts');
                                    email.setHtmlBody(htmlOutput);
                                    email.setToAddresses(toaddress);
                                    Messaging.sendEmail(New Messaging.SingleEmailMessage[]{email});
                        }
                     
            }