i have used the aggregate function sum() as follows:

query.append("select oe.name,p.productID,p.partNumber,sum(i.quantity) as quantitysum from products p"
+ " join inventoryitems as i on p.productID = i.productID"
+ " join inventoryowners io on io.inventoryitemid = i.inventoryitemid"
+ " join OEMs as oe on p.OEMID = oe.OEMID
+ " where i.statusCode in ('NEW', 'ACT', 'PHOLD', 'INACT') ");

SQLQuery sqlQuery = currentSession.createSQLQuery(query.toString());

sqlQuery.addScalar("oe.name", Hibernate.STRING);
sqlQuery.addScalar("p.productID", Hibernate.STRING);
sqlQuery.addScalar("p.partNumber", Hibernate.STRING);
sqlQuery.addScalar("quantitysum", Hibernate.INTEGER);

but while executing it i am getting the following exception:-

SQL Error: 0, SQLState: S1000
Unknown type '246 in column 5 of 6 in binary-encoded result set.

when i remove the aggregate function sum() and neccessary scalar from sqlQuery it executes properly

Database:-MySql
Hibernate Version:-3.0

the above query executes properly in MySql

This may be a problem in the mysql driver. What version are you using and is the error going away if you update to the latest?

Marius