Saturday, October 24, 2015

Complex Native SQL to JPA entity

Assuming there is a ContactDetail entity.
This could be a database table or table view.

@Entity public class ContactDetail {     private String name;     private String address;     private String phoneNo;     private String mobileNo;     private String email;     // getter and setter

the direct way to get this entity is to execute the following sql.

select name, address, phone_no, mobile_no, email from contact_detail;

another way is to select those column from different tables. 

select as name, a.address as address, b.phoneNo as phoneNo, b.mobileNo as mobileNo, as email from person p join address a on a.p_id = p.p_id join phone b on b.p_id = p.p_id join email c on c.p_id = p.p_id;

where the entity columns are actually come from different table. 
which could be a view. 
or SQL to return a table entity based on business requirement.

after gotten the correct SQL, we can proceed to query the JPA with the native SQL.

List<ContactDetail > customers = (List<ContactDetail>)em.createNativeQuery(YOUR_NATIVE_SQL, ContactDetail.class).getResultList();


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