What is CRUD?  

CRUD represents the four fundamental operations that can be performed on data:

As shown in following Figure 2 emphasizes the four basic data operations in any software application. Whether you’re storing user information, processing orders, or managing product details, these core operations—Create, Read, Update, and Delete—are essential for data management across various technology stacks. 

These operations apply to any kind of data interaction, whether in databases, APIs, or file systems. 

Why is CRUD Important?  

CRUD operations are essential because they touch every layer of an application:

• Backend Developers:  Design APIs to perform CRUD operations.
• Frontend Developers:  Call APIs to display and manipulate data. 
• Database Administrators:  Optimize CRUD queries for performance. 
• Full-Stack Developers: Implement CRUD from database to frontend.  

Service Layer & Repository  

• Service Layer: Centralizes business logic to separate it from controllers. 
• Repository: Manages database interactions using Spring Data JPA. 

Database Connection in Java  

In Java, database connections are handled using JPA, Hibernate, and JDBC. Spring Boot simplifies database connectivity with Spring Data JPA. 

CRUD Example in Java 

Note: The example language used here is Java to demonstrate CRUD operations. 

Let's implement a simple Employee Management API using Spring Boot. 

Model Class 

@Entity @Data public class Employee {   @Id   @GeneratedValue(strategy = GenerationType.IDENTITY)   private Long id;   private String name;   private String email; }

Repository

public interface EmployeeRepository extends JpaRepository {} 

Service Layer

@Service @RequiredArgsConstructor public class EmployeeService {   private final EmployeeRepository repository;
  public Employee create(Employee employee) {    return repository.save(employee); }   public List readAll() {    return repository.findAll(); }  public Employee update(Long id, Employee employee) {   Employee existing = repository.findById(id).orElseThrow(() -> new RuntimeException("Employee not found"));   existing.setName(employee.getName());   existing.setEmail(employee.getEmail());   return repository.save(existing); } public void delete(Long id) { repository.deleteById(id); } }

Controller

@RestController @RequestMapping("/employees") @RequiredArgsConstructor public class EmployeeController {  private final EmployeeService service;
 @PostMapping  public ResponseEntity create(@RequestBody Employee employee) {   return ResponseEntity.ok(service.create(employee)); } @GetMapping public ResponseEntity> readAll() {   return ResponseEntity.ok(service.readAll()); }  @PutMapping("/{id}")  public ResponseEntity update(@PathVariable Long id, @RequestBody Employee employee) {   return ResponseEntity.ok(service.update(id, employee)); }  @DeleteMapping("/{id}")  public ResponseEntity delete(@PathVariable Long id) {   service.delete(id);  return ResponseEntity.noContent().build(); } }

Conclusion 

CRUD operations are more than just simple database queries — they form the core foundation of every software application. By mastering CRUD, beginners gain a deeper understanding of how applications interact with data across different layers.  Whether you're a backend, frontend, or full-stack developer, understanding CRUD will set you on the path to becoming a proficient developer. 

Start small, practice often, and build your first CRUD-based project today!