Extract Data from a Data table to a text file in JPA - sql

Question

I'm working on data manipulation and my order is to extract all the content of a table into a text file ! I have already implemented this but apprently, I have commited a mistake while creating the request :
public void extractDonneesFichierPlat(){
TypedQuery<NotificationCnavOP> query = entityManager.createQuery("SELECT * INTO OUTFILE 'C:\\Test.txt' FROM NotificationCnavOP", NotificationCnavOP.class);
}

Answer 1

You cannot use "select * into outfile..." syntax in JPQL which is a separate query language different than SQL. If you want to execute native SQL queries in JPA you must use entityManager.createNativeQuery() method.
But still it is not possible to execute such 'bulk manipulation' query using this method.
The only solution I can think of is to use JDBC instead of JPA and execute:
Object o = entityManager.getDelegate();
System.out.println(o.getClass()); //prints the object class
// in my case it is org.hibernate.internal.SessionImpl
SessionImpl s = (SessionImpl)o;
Connection c = s.connection();
try {
Statement stmt = c.createStatement();
stmt.executeQuery("SELECT * INTO OUTFILE 'C:/Test.txt' FROM NotificationCnavOP");
} catch (SQLException e) {
e.printStackTrace();
}
The actual implementation of Session depends on the provider. In the case of Hibernate it is org.hibernate.internal.SessionImpl.
For newer versions of Hibernate it is org.hibernate.Session and it doesn't have the connection() method. So, you should try:
Object o = entityManager.getDelegate();
Session s = (Session)o;
s.doWork(connection -> {
try {
Statement stmt = connection.createStatement();
stmt.executeQuery("SELECT * INTO OUTFILE 'C:/Test2.txt' FROM NotificationCnavOP");
} catch (SQLException e) {
e.printStackTrace();
}
});
Both versions work in Hibernate 4.