where queryString = select emp.Emp_Id from employee_details emp
exception in thread "main" java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1067)
Caused by: Exception [EclipseLink-8034] (Eclipse Persistence Services - 1.1.2.v20090612-r4475): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Error compiling the query [select emp.Emp_Id from employee_details emp]. Unknown entity type [employee_details].
but when i try to insert using em.persist(obj);
the data is getting inserted,which means the connection is correct.