海阔天空

手机扫码查看

2020Javaweb教程之JDBC总结

statement执行DDL

public class TestJDBC {
    public static void main(String[] args) {
        Connection connection=null;
        Statement statement=null;
        try{
            //1.注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            //2.创建Connection对象
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/demos", "root", "root");
            //3.创建执行SQL语句的对象
            statement = connection.createStatement();
            //4.sql语句
            boolean execute = statement.execute("create table stu(id int auto_increment primary key,sname varchar(20),sex varchar(2))");
            System.out.println(execute);
        }catch (Exception e){}finally {
            try{
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            }catch (Exception e){}
        }
    }
}

statement执行DML

public class TestJDBC {
    public static void main(String[] args) {
        Connection connection=null;
        Statement statement=null;
        try{
            //1.注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            //2.创建Connection对象
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/demos", "root", "root");
            //3.创建执行SQL语句的对象
            statement = connection.createStatement();
            //4.sql语句
            //新增数据
            //int i = statement.executeUpdate("insert into gamer(gname)values ('admin')");
            //修改数据
            //int i = statement.executeUpdate("update gamer set gname='admin888' where id=2");
            //删除数据
            int i = statement.executeUpdate("delete from gamer where id=2");
            if (i > 0) {
                System.out.println("OK");
            }else{ System.out.println("ERR");}
        }catch (Exception e){}finally {
            try{
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            }catch (Exception e){}
        }
    }
}

statement执行DQL

public class TestJDBC {
    public static void main(String[] args) {
        Connection connection=null;
        Statement statement=null;
        ResultSet resultSet=null;
        try{
            //1.注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            //2.创建Connection对象
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/demos", "root", "root");
            //3.创建执行SQL语句的对象
            statement = connection.createStatement();
            //4.sql语句
            String sql="select id,sname,sex from stu";
            //5.执行SQL语句
            resultSet = statement.executeQuery(sql);
            //6.遍历
            while (resultSet.next()) {
                int id = resultSet.getInt(1);
                String sname = resultSet.getString("sname");
                String sex = resultSet.getString("sex");
                System.out.println(id+":"+sname+":"+sex);
            }
        }catch (Exception e){}finally {
            try{
                if (resultSet != null) {
                    resultSet.close();
                }
                if (statement != null) {
                    statement.close();
                }
                if (connection != null) {
                    connection.close();
                }
            }catch (Exception e){}
        }
    }
}