Spring Data / Hibernate本机查询返回null，即使实际查询返回结果

Question

So I'm trying to use the mysql datediff functions to get an average of number of days that an invoice is old.

My query looks like this:

 select avg(datediff(coalesce(nullableDateTimeColumn, now()), i.createdTimeStamp)) from invoice i 
 where i.createdTimestamp >= DATE_VARIABLE_HERE and (invoiceStatus = 'TEXT_HERE' or nullableDateTimeColumn is not null)

and my actual spring data repo definition looks like this:

@Repository
interface InternalInvoiceRepository extends PagingAndSortingRepository<Invoice, Long> {

@Query(value = "select avg(datediff(coalesce(nullableDateTimeColumn, now()), i.createdTimeStamp)) from invoice i " +
            "where i.createdTimestamp >= ?1 " +
            "and (invoiceStatus = 'TEXT_HERE' or nullableDateTimeColumn is not null)", nativeQuery = true)
    BigDecimal getAverageTimeInvoiceEntryTimeForInvoicesNewerThan(LocalDateTime time);
}

The problem is that the result is always null, I tried setting the return type to double but that also didn't work. If I set log4j.logger.org.hibernate.SQL to DEBUG and look at the sql the sql is correct. If I run the sql I get a number back, so I know the sql that is being run by hibernate is actually returning a result. The value being return is pretty small, normally between 0-5, so it's not some strange overflow error or anything else like that. This seems like a simple scenario, so I'm a little perplexed as to why this isn't working.

Versions:

Spring data: 1.9.2.RELEASE
Spring: 4.2.4.RELEASE
Hibernate: 5.0.7.Final
hibernate-jpa-2.1-api: 1.0.0.Final

Answer 1

This is for Oracle. It may helps you.

SELECT avg(TO_NUMBER(TO_CHAR(ADD_MONTHS(
(coalesce(nullableDateTimeColumn, SYSDATE)), TO_CHAR(i.createdTimeStamp, MM')), 'YYYYMMDD')))
FROM   invoice i
WHERE  i.createdTimeStamp >= '20160401' -- for example
       AND ( invoiceStatus = 'TEXT_HERE'
          OR nullableDateTimeColumn IS NOT NULL ) 

Reference here