Hibernate Query Language and Executing HQL Commands

Let us see, how to execute HQL commands..

Procedure To Execute HQL Command:

• If we want to execute execute an HQL query on a database, we need to create a query object
• ” Query ” is an interface given in org.hibernate package
• In order to get query object, we need to call createQuery() method in the session Interface
• Query is an interface, QueryImpl is the implemented class
• we need to call list method for executing an HQL command on database, it returns java.util.List
• we need to use java.util.Iterator for iterating the List collection

Syntax:

123456789Query qry = session.createQuery("--- HQL command ---");
List l = qry.list();
Iterator it = l.iterator();
while(it.hasNext())
{
  Object o = it.next();
  Product p = (Product)o;
  ----- ------- ---------
}

Notes:

• line 1: Getting the Query object
• line 2: Executing the object content (which is HQL command)
• line 3: Iterating, then while loop and type cast into our class type that’s it
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