MySQL No Dialect mapping for JDBC type: -1

List list = session.createSQLQuery(sql).list();

package xm.helper;

import java.sql.Types;

import org.hibernate.Hibernate;

import org.hibernate.dialect.MySQLDialect;

import org.hibernate.dialect.function.StandardSQLFunction;

public class XmMySQLDialect extends MySQLDialect {

public XmMySQLDialect (){

        //把报错的类型注册到hibernate类型的映射中去....

        registerHibernateType(-1, Hibernate.STRING.getName());

        //也可以把mysql类型注册到，比如hibernate支持longtext

        registerColumnType(Types.VARCHAR, "longtext");

    }

}

<property name="hibernate.dialect">xm.helper.XmMySQLDialect</property>

public List<Object[]> exeQuery(final String sql) {

        final List<Object[]> results = new ArrayList<Object[]>();

        sessionFactory.openSession().doWork(new Work() {

            public void execute(Connection paramConnection) throws SQLException {

                java.sql.PreparedStatement psta = paramConnection.prepareStatement(sql);

                ResultSet rs = psta.executeQuery();

                int columnCount = rs.getMetaData().getColumnCount();

                while(rs.next()){

                    Object[] rows = new Object[columnCount];

                       for (int j=0; j<columnCount; ++j) {

                           rows[j] = rs.getObject(j+1);

                        }

                       results.add(rows);

                    }
　　　　　　　　　 rs.close();      
                psta.close();
                paramConnection.close();

            }

        });

        return results;

    }