global class ProRegisterBatch implements Database.Batchable<sObject> {
    String regId;
    
    global ProRegisterBatch(String regId) {
        this.regId = regId;
    }

    global ProRegisterBatch() {
        
    }
    
    global Database.QueryLocator start(Database.BatchableContext BC) {
        Date yesterday = Date.Today() - 1;
        
        if (String.isBlank(this.regId)) {
            return Database.getQueryLocator([select id, ValidProductRegister__c
                                               from Product_Register__c 
                                              where ValidProductRegister__c = false
                                                and ValidTo__c = yesterday ]);

        } else {
            if (this.regId == 'updateAllInvalidData') {
                return Database.getQueryLocator([select id, ValidProductRegister__c
                                               from Product_Register__c 
                                              where ValidProductRegister__c = false ]);
                                                
            } else {
                return Database.getQueryLocator([select id, ValidProductRegister__c 
                                               from Product_Register__c 
                                              where id = :this.regId
                                                and ValidTo__c <= :Date.Today()]);    
            }
            
        }
    }

    global void execute(Database.BatchableContext BC, List<Product_Register__c> dcList) {
        
        if (dcList.size() > 0) update dcList;
    }

    global void finish(Database.BatchableContext BC) {
        
    }
}