java - How to implement with hibernate criteria Object the select query with inner join

Question

I'm new with Hibernate and Criteria Query. So I have implemented the query in HQL:

select A.mobilephone
    B.userNick
    C.creditCard
from mobile_table A
inner join user_table B
    on A.codmobile=B.codmobile
inner join Credit C 
    on A.mobileCredit= C.mobileCredit

How can I implement it with Hibernate Criteria Object?

Answer 1

Your example is just a native SQL , not the HQL . Anyway , you can use the following methods from the Criteria API to construct the desired Criteria object :

• Use the setProjection(Projection projection) to define the select clause
• Use the createCriteria(String associationPath,String alias) to define the inner join

For example , if the SQL is :

select
    TableA.columnA ,TableB.columnB ,TableC.columnC
from TableA 
inner join TableB on TableA.tableB_id=TableB.id
inner join TableC on TableA.tableC_id=TableC.id
where TableA.columnAA="AAA"
and TableB.columnBB="BBB"
and TableC.columnCC="CCC"

Then the Criteria object will be:

List<Object[]>resultList= (List<Object[]>)session.createCriteria(TableA.class, "aliasOfTableA") 
                .add(Restrictions.eq("aliasOfTableA.columnAA", "AAA"))  
                .createCriteria("aliasOfTableA.tableBId" , "aliasOfTableB")
                .add(Restrictions.eq("aliasOfTableB.columnBB", "BBB"))
                .createCriteria("aliasOfTableA.tableCId" , "aliasOfTableC")
                .add(Restrictions.eq("aliasOfTableC.columnCC", "CCC"))
                .setProjection( Projections.projectionList()
                        .add( Projections.property("aliasOfTableA.columnA") )
                        .add( Projections.property("aliasOfTableB.columnB"))
                        .add( Projections.property("aliasOfTableC.columnC") )
                ).list();

for (Object[] obj : resultList) {
        System.out.println(obj[0]); //print the value from TableA.columnA
        System.out.println(obj[1]); //print the value from TableB.columnB
        System.out.println(obj[2]); //print the value from TableC.columnC
}   

Please note that all parameters in the Criteria use the property name and class name in the mapped Java entities.