Batch Class to rename Opportunity Name

global class batchNameChange implements Database.Batchable<sObject> {

    global Database.QueryLocator start(Database.BatchableContext bc){

        Id recId = Schema.SObjectType.Opportunity.getRecordTypeInfosByDeveloperName().get('RecordTypeA').getRecordTypeId();

        system.debug('!!!!!recId!!!!!'+recId);

        return Database.getquerylocator([SELECT Id,Name,Account.Name

                                         FROM Opportunity WHERE RecordTypeId =: recId AND AccountId != NULL ]);

    }

    global void execute(Database.BatchableContext bc, List<Opportunity> records){

        system.debug('!!!!!Entered Execute!!!!!');

        List<Opportunity> finalOpp = new List<Opportunity>();

        for(Opportunity opp : records ) {

            //if(opp.Name.startsWith(opp.Account.Name))

            //*change criteria as per need*/

            if(opp.Name.contains('TEST')){

                finalOpp.add(opp);

            }

        }

        for(Opportunity opty: finalOpp) {

            system.debug('!!!!!opty!!!!!'+opty);

            system.debug('!!!!!optyName!!!!!'+opty.Name);

            system.debug('!!!!!accName!!!!!'+opty.Account.Name);

            opty.Name = opty.Account.Name + ':'+ opty.Name;

            system.debug('!!!!!opty.Name!!!!!'+opty.Name);

            //opty.Name = opty.Account.Name + ':'+ opty.Name.remove(opty.Account.Name);

            //op.Customer_Type__c = 'End User';

        }

        update finalOpp;

    }

    global void finish(Database.BatchableContext bc){

        

    }

}

Execute -

Open the Developer Console

Click Debug | Open Execute Anonymous Window

Execute the following code-

Database.executeBatch(new batchNameChange(), 200);

200 is batch size here

Output:

https://www.youtube.com/watch?v=sqVoSH-yMz0