Using a List of Values in a JdbcTemplate IN Clause in Spring JDBC

JdbcTemplate is a central class in Spring's JDBC framework, simplifying database interactions by abstracting much of the boilerplate code. A common use case involves querying the database with a dynamic list of values in the IN clause. This article will guide you through the process of using a list of values in a JdbcTemplateIN clause, ensuring efficient and secure database querying.

When you need to query the database with a variable number of parameters, the IN clause is particularly useful. However, using a list of values in the IN clause with JdbcTemplate requires careful handling to avoid SQL injection and to ensure the safe binding of parameters to the SQL query.

Key Points:

• Use ? placeholders in the SQL query.
• Convert the list to an array when passing it to JdbcTemplate.
• Use the query method for safe execution of the query.

Implementation: Using a List of Values in a JdbcTemplate IN Clause in a Spring Boot Project

Step 1: Create a New Spring Boot Project

Create a new Spring Boot project using IntelliJ IDEA or another IDE of your choice. Choose the following options:

• Project: Maven Project
• Language: Java
• Spring Boot: Latest version (3.x)

Step 2: Add Dependencies

Add the following dependencies into the Spring Boot project.

Project Structure

Once the project is created, the file structure should resemble the following:

Step 3: Configure Application Properties

In the application.properties file, configure the MySQL database connection:

spring.application.name=spring-jdbc-template-example

spring.datasource.url=jdbc:mysql://localhost:3306/testdb
spring.datasource.username=root
spring.datasource.password=mypassword
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.hibernate.ddl-auto=update
spring.sql.init.mode=always

Step 4: Create the Database Table

Create a products table in the MySQL database:

CREATE TABLE products (
 id INT AUTO_INCREMENT PRIMARY KEY,
 name VARCHAR(255) NOT NULL,
 category VARCHAR(255) NOT NULL,
 price DECIMAL(10, 2)
);

INSERT INTO products (name, category, price) VALUES 
('Laptop', 'Electronics', 1200.00),
('Headphones', 'Electronics', 150.00),
('Book', 'Books', 20.00),
('Smartphone', 'Electronics', 800.00),
('Novel', 'Books', 10.00);

Step 5: Create the Product Entity

Create a Product entity to represent the table data:

Step 6: Create the ProductRepository Class

Create a repository class to handle database operations:

Explanation:

• The SQL query is dynamically generated based on the size of the categories list.
• Collections.nCopies(categories.size(), "?"): Creates placeholders for the SQL query.
• categories.toArray() converts the list to an array, which JdbcTemplate requires for the IN clause.
• The query method executes the SQL query and maps the result set to the Product object.

Step 7: Create the ProductController Class

Create a controller to expose the API endpoint:

Step 8: Main class

The main class remains unchanged:

pom.xml file:

Step 9: Run the Application

After completing the project setup, run the application. It will start on port 8080.

Console logs:

Step 10: Test the API Endpoints

Test the API by making a GET request:

GET http://localhost:8080/products?categories=Electronics,Books

This endpoint indicates that the IN clause worked correctly with the list of the categories.

Output:

This example project provides a guide on how to use a list of values in a JdbcTemplateIN clause within a Spring Boot application, demonstrating how to integrate dynamic database queries efficiently and securely.