Monday, 18 February 2019

Spring + JdbcTemplate + Query single column value based on two parameters with object args example

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Querying Single Column Values with Multiple Parameters

In this guide, we'll dive into how to retrieve a single specific piece of data—like an employee's name—based on multiple criteria (like their ID and Age) using Spring JdbcTemplate. We'll focus on using Object Arguments to keep our code clean and flexible.

The SQL Query Design

When you need to filter your search by more than one value, you use ? placeholders in your SQL statement. This makes your query dynamic and secure:

        SELECT name FROM employee WHERE id = ? AND age = ?
    

Using Object Arguments

Spring's queryForObject method is perfect for this. By passing an Object[] array, you can handle multiple parameters easily. This approach is highly recommended for beginners because:

Readability: It separates the query logic from the actual data values.
Security: It prevents SQL Injection by using prepared statements internally.
Flexibility: The same method works for different types of data (Strings, Numbers, etc.).

Step-by-Step Implementation

Define SQL: Write your query with ? placeholders.
Prepare Args: Create an object array: new Object[] { employeeId, employeeAge }.
Execute: Call jdbcTemplate.queryForObject(sql, args, String.class).

⭐ Quick Tip:

Ensure the order of elements in your Object array matches exactly with the order of ? in your SQL query!

Watch More Tutorials

Expand your Spring JDBC knowledge with these related videos from Ram N Java:

Click here to watch on Youtube:
https://www.youtube.com/watch?v=gsXtboEKjzw&list=UUhwKlOVR041tngjerWxVccw

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Spring + JdbcTemplate + Query single column value based on two parameters with object args example

Employee.sql

CREATE DATABASE org_db;

CREATE TABLE `employee` (

  `EMPLOYEE_ID` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,

  `NAME` VARCHAR(100) NOT NULL,

  `AGE` INT(10) NOT NULL,

  `SALARY` INT(10) DEFAULT NULL,

  PRIMARY KEY (`EMPLOYEE_ID`)

) ENGINE=INNODB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;

INSERT INTO `employee` (`EMPLOYEE_ID`, `NAME`, `AGE`, `SALARY`) VALUES('1','Peter','28','80000');

INSERT INTO `employee` (`EMPLOYEE_ID`, `NAME`, `AGE`, `SALARY`) VALUES('2','John','50','40000');

INSERT INTO `employee` (`EMPLOYEE_ID`, `NAME`, `AGE`, `SALARY`) VALUES('3','David','45','20000');

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ram.core</groupId>

    <artifactId>SpringDemo</artifactId>

    <packaging>jar</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>SpringDemo</name>

    <url>http://maven.apache.org</url>

    <properties>

        <spring.version>5.0.5.RELEASE</spring.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>3.8.1</version>

            <scope>test</scope>

        </dependency>

        <!-- Spring 5 dependencies -->

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-core</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-context</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-jdbc</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <!-- MySQL database driver -->

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <version>8.0.11</version>

        </dependency>

    </dependencies>

</project>

Employee.java

package com.ram.employee.model;

public class Employee

{

    private long employeeId;

    private String name;

    private int age;

    private int salary;

    public long getEmployeeId()

    {

        return employeeId;

    }

    public void setEmployeeId(long employeeId)

    {

        this.employeeId = employeeId;

    }

    public String getName()

    {

        return name;

    }

    public void setName(String name)

    {

        this.name = name;

    }

    public int getAge()

    {

        return age;

    }

    public void setAge(int age)

    {

        this.age = age;

    }

    public int getSalary()

    {

        return salary;

    }

    public void setSalary(int salary)

    {

        this.salary = salary;

    }

    @Override

    public String toString()

    {

        return "Employee [employeeId=" + employeeId + ", name=" + name

                + ", age=" + age + ", salary=" + salary + "]";

    }

}

EmployeeDAO.java

package com.ram.employee.dao;

public interface EmployeeDAO

{

    public String findEmployeeNameByAgeAndSalary(int age, int salary);

}

EmployeeDAOImpl.java

package com.ram.employee.dao.impl;

import org.springframework.jdbc.core.support.JdbcDaoSupport;

import com.ram.employee.dao.EmployeeDAO;

public class EmployeeDAOImpl

        extends JdbcDaoSupport implements EmployeeDAO

{

    public String findEmployeeNameByAgeAndSalary(int age, int salary)

    {

        String sql = "SELECT NAME FROM EMPLOYEE WHERE Age=? and SALARY=?";

        String name = getJdbcTemplate().queryForObject(sql,

                String.class, age, salary);

        return name;

    }

}

applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-4.3.xsd">

    <bean id="dataSource"

        class="org.springframework.jdbc.datasource.DriverManagerDataSource">

        <property name="driverClassName" value="com.mysql.jdbc.Driver" />

        <property name="url" value="jdbc:mysql://localhost:3306/org_db" />

        <property name="username" value="root" />

        <property name="password" value="root" />

    </bean>

    <bean id="employeeDAO" class="com.ram.employee.dao.impl.EmployeeDAOImpl">

        <property name="dataSource" ref="dataSource" />

    </bean>

</beans>

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.employee.dao.EmployeeDAO;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        EmployeeDAO employeeDAO = (EmployeeDAO) context

                .getBean("employeeDAO");

        String name = employeeDAO.findEmployeeNameByAgeAndSalary(50,40000);

        System.out.println("name = " + name);

    }

}

Output:

Feb 09, 2019 10:25:02 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@35d176f7: startup date [Sat Feb 09 10:25:02 IST 2019]; root of context hierarchy

Feb 09, 2019 10:25:03 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

Feb 09, 2019 10:25:04 AM org.springframework.jdbc.datasource.DriverManagerDataSource setDriverClassName

INFO: Loaded JDBC driver: com.mysql.jdbc.Driver

Sat Feb 09 10:25:13 IST 2019 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

name = John