JDBC练习

练习：
account表 添加一条记录

public class JdbcDemo02 {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
        Class.forName("com.mysql.cj.jdbc.Driver");
        String sql = "insert into account values(null,'王五',3000.0)";
        Connection coon = DriverManager.getConnection("jdbc:mysql://localhost:3306/root", "root", "root");
        Statement stmt = coon.createStatement();
        int count = stmt.executeUpdate(sql);
        if (count > 0){
            System.out.println("添加成功");
        }else{
            System.out.println("添加失败");
        }

    }
}

account表 修改记录

public class JdbcDemo01 {
    public static void main(String[] args) throws Exception {
        //注册驱动
        Class.forName("com.mysql.cj.jdbc.Driver");
        //获取数据库连接对象
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/root", "root", "root");
        //定义sql
        String sql = "update account set balance = 1000 where id = 3";
        //获取执行sql语句的对象 Statement
        Statement stmt = conn.createStatement();
        //执行sql，接受返回结果
        int count = stmt.executeUpdate(sql);
        //处理结果
        System.out.println(count);
        //释放资源
        conn.close();
        stmt.close();


    }
}

account表 删除一条记录

public class JdbcDemo03 {
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.cj.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/root", "root", "root");

        String sql = "delete from account where id = 5";
        Statement sttm = conn.createStatement();
        int i = sttm.executeUpdate(sql);

        if (i > 0){
            System.out.println("删除成功");
        }else {
            System.out.println("删除失败");
        }
    }
}