前提：

首先要对java与数据库进行连接哦！
连接步骤
https://blog.csdn.net/hanhanwanghaha/article/details/105716885

代码如下：

增：

@Test//数据插入public void demo1() {Connection conn=null;Statement stmt=null;try {//注册驱动Class.forName("com.mysql.jdbc.Driver");//创建连接conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/name","root","123456");//执行sql对象stmt=conn.createStatement();String sql="INSERT INTO person VALUES(NULL,'eee','741','小白')";//返回1个整型int i=stmt.executeUpdate(sql);if(i>0) {System.out.println("插入成功！");}}catch(Exception e){e.printStackTrace();}finally {//释放资源if(conn!=null) {try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}conn=null;}if(stmt!=null) {try {stmt.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}stmt=null;}}}

删:

@Test//数据删除public void demo3() {Connection conn=null;Statement stmt=null;try {//注册驱动Class.forName("com.mysql.jdbc.Driver");//建立连接conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/name","root","123456");//创建sql语句String sql="delete from person where id=5";stmt=conn.createStatement();int i=stmt.executeUpdate(sql);if(i>0) {System.out.println("删除成功！");}}catch(Exception e) {e.printStackTrace();}finally {//释放资源if(conn!=null) {try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}conn=null;}if(stmt!=null) {try {stmt.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}stmt=null;}}}

改：

@Test//数据更新public void demo2() {Connection conn=null;Statement stmt=null;try {//注册驱动Class.forName("com.mysql.jdbc.Driver");//建立连接conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/name","root","123456");//创建sql语句String sql="update person set username='qqq',password='852',address='小陈'   where id=3";//创建sql执行对象stmt=conn.createStatement();int i=stmt.executeUpdate(sql);if(i>0) {System.out.println("修改成功");}else {System.out.println("修改失败");}}catch(Exception e) {e.printStackTrace();}finally {//释放资源if(conn!=null) {try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}conn=null;}if(stmt!=null) {try {stmt.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}stmt=null;}}}

查：

@Testpublic void demo2() {try {//1.加载驱动DriverManager.registerDriver(new Driver());//2.创建连接Connection conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/name", "root", "123456");//是不是自己的账户和密码//3.1创建sql语句对象String sql="select * from person";Statement stmt=conn.createStatement();//3.2执行sql语句并进行遍历ResultSet resultSet=stmt.executeQuery(sql);while(resultSet.next()) {int uid=resultSet.getInt("id");String username=resultSet.getString("username");String password=resultSet.getString("password");String address=resultSet.getString("address");System.out.println(uid+" "+username+" "+password+" "+address+" ");}//4.释放相关资源resultSet.close();stmt.close();conn.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}

注意：我的数据库为name，表名为person,用户名为root,密码为123456，你需要根据自己的表进行改正。
希望对你有用！

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