Simplify MySQL database operations through an ORM framework written in Java

With the development of the Internet, data has become one of the most important assets of an enterprise. The wide application of the relational database MySQL also makes the operation of the MySQL database particularly important. However, in the daily development and maintenance process, we often encounter complex SQL statements, which often require a lot of time and energy to study and optimize. At this time, a framework called ORM (Object-Relational Mapping) came into being, which can easily map Java objects to the database and avoid cumbersome SQL operations. This article will introduce a method written in Java ORM framework to simplify the operation of MySQL database.

1. What is an ORM framework?

ORM is the abbreviation of Object/Relational Mapping. The basic idea is to map data between Java objects and relational databases, so that object-oriented programming programs can add, delete, modify, and query data as easily as operating databases without having to write SQL statements. .

ORM framework is a tool to implement ORM ideas. The ORM framework can map defined Java classes to database tables and convert attributes in Java classes into columns in the database, thereby realizing automatic mapping of data and simplification of data operations.

2. Why use ORM framework?

Using the ORM framework can bring the following benefits to developers:

1. Convenient operation of the database: Using the ORM framework can encapsulate SQL statements. For developers, they only need to define With good Java classes and properties, you can easily perform database operations without having to worry about the underlying SQL statements.
2. Improve development efficiency: Using the ORM framework can greatly improve development efficiency. Developers only need to focus on the implementation of business logic and do not have to care about the implementation of database-related code.
3. Reduce the error rate: Using the ORM framework can separate business logic and database operations, reducing the coupling of the code, making it easier to maintain and modify, and also reducing the possibility of errors.

3. Introducing the ORM framework written in Java

In Java, there are many ORM frameworks, such as Hibernate, Mybatis, JPA, etc. In this article, we introduce the ORM framework written in Java-ActiveJDBC. It is a simple ORM framework that is simple, easy to learn, easy to use, and easy to expand.

ActiveJDBC is based on ActiveRecord mode, so Java classes correspond to database tables, and one Java class corresponds to one database table. Properties in Java classes map to fields in database tables.

The database types supported by ActiveJDBC include not only MySQL, but also many database types such as PostgreSQL, Oracle, and Microsoft SQL Server.

4. Use ActiveJDBC to operate the MySQL database

Below, we take the MySQL database as an example to introduce how to use the ActiveJDBC framework to operate the database.

1. Add dependencies

In the Maven project, we need to add the following dependencies in the pom.xml file:

<dependency>
    <groupId>org.javalite</groupId>
    <artifactId>activejdbc</artifactId>
    <version>1.4.13</version>
</dependency>

In the Gradle project, we The following dependencies need to be added to the build.gradle file:

compile 'org.javalite:activejdbc:1.4.13'

2. Define Java classes

When using the ActiveJDBC framework, we need to define Java classes that inherit from the Model class. In the MySQL database, we can take the user table as an example and first define a User class:

@Table("users")
public class User extends Model{}

Among them, the @Table annotation indicates that the Java class corresponds to the users table in MySQL.

3. Establishing a connection

Before performing database operations, we need to establish a connection with the MySQL database first. In the ActiveJDBC framework, we can establish connections through JDBC configuration. In our project, we can create a db.properties file in the src/main/resources/ directory to configure the connection information of the MySQL database:

driver=com.mysql.jdbc.Driver
username=root
password=123456
url=jdbc:mysql://localhost:3306/test

Among them, driver represents the MySQL driver; username and Password represents the user name and password of the MySQL database; url represents the address and port number of the MySQL database to be accessed.

Use the following code to load the properties in the configuration file and establish a connection with the MySQL database:

Properties props = new Properties();
props.load(new FileInputStream("src/main/resources/db.properties"));
Base.open(props.getProperty("driver"), props.getProperty("url"), props.getProperty("username"), props.getProperty("password"));

4. Operation on the database

After establishing After connection, we can easily operate the MySQL database through the ActiveJDBC framework. The following are some commonly used database operation example codes:

Query:

List<User> userList = User.where("age > ?", 20);

The above code indicates querying user data older than 20 years old.

Insert:

User user = new User();
user.set("name", "tom");
user.set("age", 25);
user.saveIt();

The above code means inserting a new user record.

Update:

User user = User.findById(1);
user.set("age", 30);
user.saveIt();

The above code indicates that the age of the user with update number 1 is 30 years old.

Delete:

User user = User.findById(1);
user.delete();

The above code means to delete the user record numbered 1.

5. Summary

This article introduces the use of ORM framework ActiveJDBC written in Java to simplify the operation of MySQL database. By using the ActiveJDBC framework, we can easily map Java objects to the MySQL database and avoid cumbersome SQL operations. Through the introduction of this article, I believe that everyone has a deeper understanding of the ORM framework and can flexibly use the ORM framework in actual development.

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