Executing a subquery using a criteria

In this recipe, we will take a look at how to use subquery. Here, we will do the same thing as before; we will use the DetachedCriteria class provided by the hibernate API. The DetachedCriteria class works in detached mode and is used to create a criteria query when the session is not available, as we can execute DetachedCriteria with the existing session object.

How to do it…

We will create one scenario to show how DetachedCriteria acts as a subquery.

The scenario is to get all the products whose categories have been recently added.

The preferred solution for this problem is as follows:

• First, we will create DetachedCriteria to find the maximum createdOn date

• Then, we will use the result of the first query to check the date of the product's category

Consider the following code:

Code

/* Line 1 */ DetachedCriteria detachedCriteria = DetachedCriteria.forClass(Category.class);
/* Line 2 */ detachedCriteria.setProjection(Projections.max("createdOn"));

/* Line 4...