JDBC的增删改查

版权声明：JAVA https://blog.csdn.net/weixin_43190126/article/details/84846701

package com.qyl.dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import org.junit.Test;

public class TestDao {
	
	
	/**
	 * 获取链接
	 * @throws ClassNotFoundException 
	 */
	@Test
	public void testGetConn() throws Exception {
		//加载驱动
		Class.forName("com.mysql.jdbc.Driver");
		//获取链接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "123456");
		
		Thread.sleep(5000);
		
		System.out.println(conn);
		
	}
	
	
	//创建表
	/**
	 * 贾琏欲执事 DDL
	 */
	@Test
	public void testCreatTable() throws Exception {
		//加载驱动
		Class.forName("com.mysql.jdbc.Driver");
		//获取链接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/product", "root", "123456");
		//获取语句对象
		Statement st = conn.createStatement();
		//sql
		String sql = "CREATE TABLE dept(id bigint(20) NOT NULL AUTO_INCREMENT,name varchar(255) DEFAULT NULL,PRIMARY KEY (`id`))"; 
		//执行语句
		st.executeUpdate(sql);
		//释放资源
		st.close();
		conn.close();
	}
	
	//增添
	@Test
	public void testCreatTable() throws Exception {
		//加载驱动
		Class.forName("com.mysql.jdbc.Driver");
		//获取链接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/product", "root", "123456");
		//获取语句对象
		Statement st = conn.createStatement();
		//sql
		String sql = "insert into dept(id,name) values (\"1\",'张三')"; 
		//执行语句
		st.executeUpdate(sql);
		//释放资源
		st.close();
		conn.close();
	}
	
	
	//修改
	@Test
	public void testCreatTable() throws Exception {
		//加载驱动
		Class.forName("com.mysql.jdbc.Driver");
		//获取链接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/product", "root", "123456");
		//获取语句对象
		Statement st = conn.createStatement();
		//sql
		String sql = "UPDATE dept set name = \"张五\" WHERE id = 3"; 
		//执行语句
		st.executeUpdate(sql);
		//释放资源
		st.close();
		conn.close();
	}
	
	
	//删除
	@Test
	public void testDelete() throws Exception {
		Connection conn = null;
		Statement st = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/product", "root", "123456");
			 st = conn.createStatement();
			st.executeUpdate("DELETE from dept WHERE id = 3"); 	
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			try {
				if(st!=null)st.close();
			} catch (Exception e) {
				e.printStackTrace();
			}finally {
				try {
					if(conn!=null)conn.close();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
	}
	
	
	
	//单个查询
	/**
	 * 贾琏欲执事 DQL
	 */
	@Test
	public void testGetOne() throws Exception {
		Dept dept = new Dept();
		
		//加载驱动
		Class.forName("com.mysql.jdbc.Driver");
		//获取链接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/product", "root", "123456");
		//获取语句对象
		Statement st = conn.createStatement();
		//sql
		String sql = "select * from dept where id = 2"; 
		//执行语句
		ResultSet result = st.executeQuery(sql);
		
		while (result.next()) {
			dept.setId(result.getInt("id"));
			dept.setName(result.getString("name"));
		}
		//释放资源		
		st.close();
		conn.close();
		System.out.println(dept);
	}
	
	
	//多个查询
	/**
	 * 贾琏欲执事 DQL
	 */
	@Test
	public void testGetAll() throws Exception {
		ArrayList<Dept> list = new ArrayList<>();
		
		//加载驱动
		Class.forName("com.mysql.jdbc.Driver");
		//获取链接
		Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/product", "root", "123456");
		//获取语句对象
		Statement st = conn.createStatement();
		//sql
		String sql = "select * from dept"; 
		//执行语句
		ResultSet result = st.executeQuery(sql);
		
		while (result.next()) {
			Dept dept = new Dept();
			dept.setId(result.getInt("id"));
			dept.setName(result.getString("name"));
			list.add(dept);
		}
		//释放资源
		result.close();
		st.close();
		conn.close();
		System.out.println(list);
		
	}
	
}

其中的一些sql语句根据实际情况做修改，还有连接密码与数据库，必要的话也做一些修改；