mysql数据库增删改查

package DButls;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.List;

public class JDBCTest {
    public <T> List<T> query(Class<T> clazz, String sql){
        return null;
    }
    /*
    resultset 是封装JDBC的结果集
    1.调用 statement 的对象executeQuery 就能够获得结果集
    ResultSet 返回的实际上就是一张数据表. 有一个指针指向数据表的第同样的前面.
    * 能够调用 next() 方法检测下一行是否有效. 如有效该方法返回 true, 且指针下移. 至关于
    * Iterator 对象的 hasNext() 和 next() 方法的结合体
    * 3. 当指针对位到一行时, 能够经过调用 getXxx(index) 或 getXxx(columnName)
    * 获取每一列的值. 例如: getInt(1), getString("name")
    * 4. ResultSet 固然也须要进行关闭.
     */

    public void testResultset(){
        //获取ID是4的student
        Connection connection = null;//链接
        Statement statement =null;
        ResultSet resultSet = null;
        try{
            //1 获取数据库链接
            connection = JDBCTools.getConnection();
            System.out.println(connection);
            //2.获取statement
            statement = connection.createStatement();
            System.out.println(statement);
            //3准备mysql
            String sql = "SELECT * FROM STUDENTS";
            resultSet = statement.executeQuery(sql);
            System.out.println(resultSet);
            //处理返回的结果集
            while (resultSet.next()){
                int id = resultSet.getInt(1);
                String name = resultSet.getString("name");
                String age = resultSet.getString("age");
                System.out.print("id = "+id);
                System.out.print("name = "+name);
                System.out.println("age = "+age);


            }


        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JDBCTools.release(resultSet, statement, connection);
        }
    }


    /*
    执行插入  修改   删除
     */
        public void TestInsert()throws  Exception{
            Connection connection = null;
            Statement statement = null;
            try{
                String sql = "INSERT INTO students(NAME,age)VALUES(\"bbbb\",\"57\")";
                connection = JDBCTools.getConnection();
                statement = connection.createStatement();
                statement.executeUpdate(sql);
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                JDBCTools.release(statement, connection);
            }
        }

        //删除数据库
        public void  TesTdelect(){
            Connection connection = null;
            Statement statement = null;
            try{
                String sql="DELETE FROM students WHERE id > 3";
                connection = JDBCTools.getConnection();
                statement = connection.createStatement();
                statement.executeUpdate(sql);
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                JDBCTools.release(statement, connection);
            }
        }
        //尝试修改数据
        public void TestUpdate() throws  Exception{
            Connection connection = null;
            Statement statement = null;
            try {
                String sql = "UPDATE students SET age = '200' where name  = 'zhangsan' ";
                connection = JDBCTools.getConnection();
                statement = connection.createStatement();
                statement.executeUpdate(sql);
            }catch (Exception e){
                e.printStackTrace();
            }finally {
                JDBCTools.release(statement, connection);
            }
        }

}