无法在springboot和Data JPA中使用nativeQuery方法访问数据记录

Question

I tried nativeQuery method for fetching some data without using JPQL in my repository file using Spring Boot , Spring Data JPA method, I am adding my sample code below:

public interface UsersRepository extends CrudRepository<Users, Long> {
  @Query(value = "select u.username from users u",nativeQuery=true)
  List<Users> findByUsername();
},

And calling the method by,

UsersRepository userRepo;
return (List<Users>) userRepo.findByUsername();

Then the error I am getting:

"There was an unexpected error (type=Internal Server Error, status=500). could not execute query; SQL [select u.username from users u]; nested exception is org.hibernate.exception.SQLGrammarException: could not execute query".

Can anyone help to solve this issue?

Answer 1

You are using nativeQuery which always results in a projection and you try to map that into the List of Users entity.

This wont work, you have expect a List<String> in your case. Or List if you decide to add more columns in the result at some point.

@Query(value = "select u.username from users u",nativeQuery=true)
  List<String> findByUsername();

Also make sure that the table in the database is actually cassed users and the column is username . If you are using the entity name and field name then that is another thing to change.