select max native query hibernate - mysql

Question

I am trying to get the max value of a column in a table using a native query with the #Query annotation
I tried to derive it from the examples here: https://www.baeldung.com/spring-data-jpa-query
#Query(value = "SELECT max(i.sequence) " +
"FROM invoices as i " +
"WHERE i.fleet_id = ?1", nativeQuery = true)
Long findMaxSequence(String fleetId);
i ve also tried:
#Query(value = "SELECT max(i.sequence) " +
"FROM invoices as i " +
"WHERE i.fleet_id = :fleetId", nativeQuery = true)
Long findMaxSequence(#Param("fleetId") String fleetId);
When i call my method as :
long maxSeq = invoiceRepository.findMaxSequenceForFleetId(invoice.getFleetId());
I get a NullPointerException. Any ideas why?
Invoice entity looks like this :
#Entity
#Table(name = "invoices"}
public class Invoice implements Serializable {
#Id
private String id;
#Column
private long sequence;
#Column(length = 12)
private String fleetId;
// ...
}

Answer 1

The issue was due to the fact that the database was empty so the query was returning null
and basic types such as long cannot be assigned to null values. Weirdly the compiler did not complain..
I modified my code as below:
Long maxSeq = invoiceRepository.findMaxSequenceForFleetId(invoice.getFleetId());
if(maxSeq == null){
maxSeq = 0L;
}