Consulta personalizada de Hibernate para la pantalla de búsqueda

I have search screen which has 10 fields and involves around 5 to 6 tables to get the result. I am writing a custom SQL query and appending where condition only when a value exists.

Can someone please suggest is this the right approach or any other better way.

I cannot use any plugins or additional APIs for my situation.

StringBuffer sqlQuery = new StringBuffer();
sqlQuery.append (" select member.* from member, customer, case where customer.status='A');
if(firstName != null)
sqlQuery.append("customer.firstName= :firstName");

if(caseid != null)
sqlQuery.append("case.caseid =:caseid");

SQLQuery queryObj = createSQLquery(sqlQuery.toString());
queryObj.list();

mientras que member, customer, case are actual tables.

ACTUALIZACIÓN

when I am adding where condition to string buffer

if(caseid != null)
sqlQuery.append(" and case.caseid =:caseid");

and when queryObj is formed I am doing it as
if(caseid != null)
queryObj.setString("caseid", caseid);

is there better way to add after queryObj (to combine both)?

Gracias de antemano.