Query Optimization Using QueryDSL in a Spring Boot Application – DS

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Query Optimization Using QueryDSL in a Spring Boot Application – DS

What Is QueryDSL?

QueryDSL (Query Domain Specific Language) is a Java-based framework. It is a type-safe, fluent API for building SQL-like queries in a programmatic way.

Official Documentation for the latest version of QueryDSL 

Key Features and Concepts of QueryDSL

  • Type Safety: 
  • Code Generation
  • JPA Integration
  • Support for Collections
  • DSL for Expressing Predicates
  • Support for Joins
  • Extensibility

Process of Query Optimization Using QueryDSL

To optimize query using QueryDSL in spring boot application, We have to follow below points.

1) Add dependency for QueryDSL in your application:


2) Create An entity Class Testing with Primary key and two other column:

public class Testing {
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String firstName;
    private String lastName;

3) Create an Repository class for custom functions:

import org.springframework.beans.factory.annotation.Autowired;

import com.querydsl.jpa.impl.JPAQueryFactory;

public class TestingRepository {
    private EntityManager entityManager;

    public List<Testing> findPeopleByLastName(String lastName) {
        JPAQueryFactory queryFactory = new JPAQueryFactory(entityManager);
        QTesting person = QTesting.testing;
        return queryFactory.selectFrom(person)

4) Create Database table

CREATE TABLE `testing` (
  `first_name` varchar(45) DEFAULT NULL,
  `last_name` varchar(45) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

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