java experts can you please help me write detached queries as a part of the criteria query for the following SQL statement.
select A.*
FROM AETABLE A
where not exists
(
select entryid
FROM AETABLE B
where B.classpk = A.classpk
and B.userid = A.userid
and B.modifiedDate > A.modifiedDate
)
and userid = 10146
The detached criteria allows you to create the query without Session . Then you can execute the search in an arbitrary session. In fact you should think carefully when using a detached criteria using another, or a new, session (no cache, and creation of the session).
Hibernate provides alternate ways of manipulating objects and in turn data available in RDBMS tables. One of the methods is Criteria API, which allows you to build up a criteria query object programmatically where you can apply filtration rules and logical conditions.
The CriteriaQuery interface defines the orderBy method to order query results according to attributes of an entity.
Criteria in Hibernate can be used for join queries by joining multiple tables, useful methods for Hibernate criteria join are createAlias(), setFetchMode() and setProjection() Criteria in Hibernate API can be used for fetching results with conditions, useful methods are add() where we can add Restrictions.
You need to write a correlated subquery. Assuming property / class names match column / table names above:
DetachedCriteria subquery = DetachedCriteria.forClass(AETable.class, "b")
.add(Property.forName("b.classpk").eqProperty("a.classpk"))
.add(Property.forName("b.userid").eqProperty("a.userid"))
.add(Property.forName("b.modifiedDate").gtProperty("a.modifiedDate"));
Criteria criteria = session.createCriteria(AETable.class, "a")
.add(Property.forName("userid").eq(new Integer(10146)))
.add(Subqueries.notExists(subquery);
Just one addition to the above query. If the entryid is not the primary key, then you'll need to add projection.
DetachedCriteria subquery = DetachedCriteria.forClass(AETable.class, "b")
.add(Property.forName("b.classpk").eqProperty("a.classpk"))
.add(Property.forName("b.userid").eqProperty("a.userid"))
.add(Property.forName("b.modifiedDate").gtProperty("a.modifiedDate"))
.add(setProjection(Projections.property("entryId")); // Additional projection property
Criteria criteria = session.createCriteria(AETable.class, "a")
.add(Property.forName("userid").eq(new Integer(10146)))
.add(Subqueries.notExists(subquery);
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