Entity Class name is transformed into SQL table name with underscores

Spring by default uses org.springframework.boot.orm.jpa.SpringNamingStrategy which splits camel case names with underscore. Try setting spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.EJB3NamingStrategy in application.properties. Check out this and this for more info.

For hibernate v5:

spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

For Spring Boot 2 (checked with 2.2.6.RELEASE) it should be configuration yml file:

spring:
  jpa:
    hibernate:
      naming:
        physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

So you could have model like:

@Table(name = "tblDepartments")
public class Department {
    @Id
    @Column(name = "dpID")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @NotEmpty
    @Size(min = 1, max = 25)
    @Column(name = "dpName", length = 25)
    private String name;

and populate tables at startup with data.sql:

INSERT INTO tblDepartments (dpName) VALUES ('Gryffindor');
INSERT INTO tblDepartments (dpName) VALUES ('Hufflepuff');