How to store form data using database in Java?

How to use a database to store form data in Java

Introduction: In web development, forms are a common way of data interaction. Storing form data in the database is an important step in achieving data persistence. This article will introduce how to use a database to store form data in Java, with code examples.

1. Database preparation
Before using the database to store form data, you must first prepare the database environment. We can use relational databases such as MySQL or Oracle. In this article, we will use the MySQL database. Create a database named "form_data" and create a data table named "form_table" under the database.

The SQL to create the data table is as follows:

CREATE DATABASE form_data;
USE form_data;
CREATE TABLE form_table (
   id INT PRIMARY KEY AUTO_INCREMENT,
   name VARCHAR(50),
   age INT,
   email VARCHAR(50)
);

2. Import the database driver
When using a database in Java, you need to import the corresponding database driver. For the MySQL database, we need to import the MySQL database driver. The driver can be imported in the following ways:

import java.sql.*;

3. Connect to the database
In Java, you can use JDBC (Java Database Connectivity) to connect to the database. Before connecting to the database, you need to set the database URL, username and password. The code example is as follows:

Connection conn = null;
PreparedStatement stmt = null;

try {
    String url = "jdbc:mysql://localhost/form_data";
    String username = "root";
    String password = "123456";

    //加载数据库驱动程序
    Class.forName("com.mysql.cj.jdbc.Driver");

    //建立数据库连接
    conn = DriverManager.getConnection(url, username, password);

    //执行数据库操作
    //...
} catch (Exception e) {
    e.printStackTrace();
} finally {
    //关闭数据库连接
    try {
        if (stmt != null) stmt.close();
        if (conn != null) conn.close();
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

4. Insert data into the database
After connecting to the database, we can use the PreparedStatement object to execute SQL statements and insert form data into the database. The code example is as follows:

try {
    //建立数据库连接
    //...

    //准备SQL插入语句
    String sql = "INSERT INTO form_table (name, age, email) VALUES (?, ?, ?)";
    stmt = conn.prepareStatement(sql);

    //设置参数
    stmt.setString(1, "张三");
    stmt.setInt(2, 20);
    stmt.setString(3, "zhangsan@example.com");

    //执行插入操作
    stmt.executeUpdate();

    System.out.println("数据插入成功！");
} catch (SQLException e) {
    e.printStackTrace();
}

5. Query data
In addition to inserting data, we can also use PreparedStatement objects to execute query statements and read form data from the database. The code examples are as follows:

try {
    //建立数据库连接
    //...

    //准备SQL查询语句
    String sql = "SELECT * FROM form_table";
    stmt = conn.prepareStatement(sql);

    //执行查询操作
    ResultSet rs = stmt.executeQuery();

    //遍历查询结果
    while (rs.next()) {
        int id = rs.getInt("id");
        String name = rs.getString("name");
        int age = rs.getInt("age");
        String email = rs.getString("email");

        System.out.println("id: " + id + ", name: " + name + ", age: " + age + ", email: " + email);
    }

    rs.close();
} catch (SQLException e) {
    e.printStackTrace();
}

6. Summary
This article introduces how to use a database to store form data in Java and gives code examples. Through the process of connecting to the database, inserting data and querying data, we can further learn and practice database operations. I hope this article will help readers use databases to store form data in Java development.

References:
1. "Java Programming Thoughts" - Bruce Eckel
2.https://www.w3schools.com/java/java_mysql_insert.asp

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