How to make Entity class for database table

Spring Boot Entity Class

Step1: We need the Entity class to map the database table. 

Step2: So the table column should be the same as a variable name in the entity class.

Step3: Make class same as given by dilsecodie, then @columns changes as per your table columns name,

    Then create a Setter /getter method to use this class.

Step4: change @Table name as your table.

No Java class whether an entity or whatever should ever make an assumption about the implementation of the data architecture of the database, whether it is tables or keys or whatever. Because the moment Java class or any application makes that assumption, the database architecture itself starts to become immutable. It's kind of like the petrification of a piece of wood. The more the application knows about the implementation of the data architecture, the more "in stone" it becomes. Every entity class should access the database through, at minimum, a view and preferably a stored procedure. Always consider any Java class as denormalized data.

Any synthetic or surrogate key used by an entity should ideally be a shadow key and keep the primary keys invisible from the application entity classes. Otherwise, a day will come when someone will have to confront the problem where the customer entity in the OLTP database has a different customer number than the customer entity in the CRM database. Shadow keys can be computed just like primary keys, but not used as foreign keys in queries. The denormalized version of the data uses the shadow key. 

I assume the entity class refers to JPA Entity. JPA uses an entity to map the database relationship. The access to the database is normally the responsibility of EntityManager. Of course, if you must write some code accessing database using JDBC, that's your choice other than the recommended way for JPA.

@Entity 

public class Customer { 

 

  @Id 

  @GeneratedValue(strategy=GenerationType.AUTO) 

  private Long id; 

  private String firstName; 

  private String lastName; 

 

  protected Customer() {} 

 

  public Customer(String firstName, String lastName) { 

    this.firstName = firstName; 

    this.lastName = lastName; 

  } 

 

  @Override 

  public String toString() { 

    return String.format( 

        "Customer[id=%d, firstName='%s', lastName='%s']", 

        id, firstName, lastName); 

  } 

 

  public Long getId() { 

    return id; 

  } 

 

  public String getFirstName() { 

    return firstName; 

  } 

 

  public String getLastName() { 

    return lastName; 

  } 

}

Entity: An entity represents a single instance of your domain object saved into the database as a record. It has some attributes that we represent as columns in our tables.

Model: A model typically represents a real-world object that is related to the problem or domain space. In programming, we create classes to represent objects. These classes, known as models, have some properties and methods (defining object's behavior) 

Note*: Still having Problem, can ask in doubt section.