JDBC

• 数据库连接的步骤
• 编译时不依赖的数据库连接代码

数据库连接的步骤

第一步：注册驱动
第二步：获取连接
第三步：获取statement对象
第四步：执行SQL语句返回结果集
第五步：遍历结果集
第六步：关闭连接释放资源

编译时不依赖的数据库连接代码

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JDBCDemo {
	private static final String url = "jdbc:mysql://localhost:3306/demo?serverTimezone=GMT%2B8";
	private static final String user = "root";
	private static final String password = "362522";
	static Connection connection = null;
	static Statement stmt = null;
	static ResultSet rs1 = null;
	public static void update(){   //增、删、改
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
			// a、加载具体的驱动类
			//connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/demo?useSSL=false&serverTimezone=UTC","root","362522");
			connection = DriverManager.getConnection(url, user, password);
			//b、连接数据库
			stmt = connection.createStatement();
			//c、操作数据库
			/*
			String sql1 = "insert into student value('9','aud','68')";
			int count =	stmt.executeUpdate(sql1);//执行sql语句，增、删、改,返回执行结果
			if (count > 0) {
				System.out.println("操作成功！");
			}
			*/
			String sql = "select * from student";
			ResultSet rs1 = stmt.executeQuery(sql);
			while (rs1.next()){
				int sid = rs1.getInt("sid");
				String name = rs1.getString("sname");
				double score = rs1.getDouble("score");
				System.out.println(sid+"  "+name+"  "+score);
			}
			
		} catch (ClassNotFoundException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}finally{
			try {
				if (rs1 !=null){
					rs1.close();
				}
				if (stmt != null) {
					stmt.close();
				}
				if (connection != null) {
					connection.close();
				}
			} catch (SQLException e) {
				// TODO 自动生成的 catch 块
				e.printStackTrace();
			}
		}
	}
	public static void main(String[] args){
		update();
	}
}