休眠查询返回null

Question

I have this query in java-hibernate and I want to return this result. But returns null. How can I fix it?

BigDecimal totalbalance = null;
Query query = session.createQuery("select sum(beforeBalance) from DepositTransaction");
totalbalance = (BigDecimal) query;

return new BigDecimal(totalbalance+"");

Answer 1

Your HQL syntax is a bit off. Try this instead:

BigDecimal totalbalance = null;
String theQuery = "select sum(dt.beforeBalance) from DepositTransaction dt";
Query query = session.createQuery(theQuery);
totalbalance = (BigDecimal) query.getSingleResult();

return totalbalance;

This assumes that your DepositTransaction class has a field called beforeBalance with a getter method.

Answer 2

first you have to execute the query:

List<BigDecimal> result = (List<BigDecimal>)query.list();

Then you have to check the result

if (result.length()!=0){
   return result.get(0)
}
return null;

Answer 3

Try this,

totalbalance = (BigDecimal) query.getSingleResult();
return totalbalance;

instead of

totalbalance = (BigDecimal) query;

Answer 4

As that look like a native query you should use createNativeQuery. You should also only look for a single result so use getSingleResult

BigDecimal totalbalance = null;
String yourQuery = "select sum(dt.beforeBalance) from DepositTransaction dt";
Query query = session.createNativeQuery(yourQuery);
return new BigDecimal((BigDecimal) query.getSingleResult());

Answer 5

Approach using SQLQuery object:

String query = "select sum(beforeBalance) from DepositTransaction";
BigDecimal totalBalance = (BigDecimal)session.createSQLQuery(query).list().get(0);
return totalBalance;

Answer 6

试试这个totalbalance = (BigDecimal)query.uniqueResult();