package com.sjx.a;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import org.junit.Test;
  //1. next方法,向下移动并判断是否有内容
  //2. getXXX方法,根据列索引或列名获得列的内容
public class Demo {
  @Test
  public void fun1() throws Exception{
    //1 注册驱动
    Class.forName("com.mysql.jdbc.Driver");
    //2 获得连接
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/day05", "root", "1234");
    //3 创建Statement
    Statement st = conn.createStatement();
    //4 书写sql
    String sql = "select * from t_user" ;
    //5 执行sql
    ResultSet rs = st.executeQuery(sql);
    //向下移动一行,并判断
    while(rs.next()){
      //有数据
      //取数据:getXXX 
      int id = rs.getInt(1);//获得第一列的值
      //int id rs.getInt("id");// 获得id列的值
      String name = rs.getString(2);//获得第二列的值
      int age = rs.getInt(3);//获得第三列的值
      System.out.println(id+"==>"+name+"==>"+age);
      
      //rs.gettimestamp(columnIndex)
    }
    //6关闭资源
   st.close();
   conn.close();
  }
  /* 数据库类型      java类型
    int         int
    double       double
    decimal       double
    char       String
    varchar       String
    datetime     Date
    timestamp    Timestamp/Date
   */
}

package com.sjx.a;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import org.junit.Test;
public class Demo2 {
  @Test
  public void fun1() throws Exception{
    //1 注册驱动
    Class.forName("com.mysql.jdbc.Driver");
    //2 获得连接
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/day05", "root", "1234");
    //3 创建Statement
    Statement st = conn.createStatement();
    //4 书写sql
    String sql = "select * from t_user" ;
    //5 执行sql
    ResultSet rs = st.executeQuery(sql);
    //倒着遍历
      //1> 光标移动到最后一行之后
      rs.afterLast();
      //2> 遍历=>
      while(rs.previous()){//向上移动光标,并判断是否有数据
        int id = rs.getInt("id");// 获得id列的值
        String name = rs.getString("name");//获得第二列的值
        int age = rs.getInt("age");//获得第三列的值
        System.out.println(id+"==>"+name+"==>"+age);
      }
    //6关闭资源
   st.close();
   conn.close();
  }
  /* 数据库类型      java类型
    int         int
    double       double
    decimal       double
    char       String
    varchar       String
    datetime     Date
    timestamp    Timestamp/Date
   */
}

package com.sjx.a;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import org.junit.Test;
//ResultSet细节
// 2.结果集反向修改数据库
public class Demo3 {
  @Test
  public void fun1() throws Exception{
    //1 注册驱动
    Class.forName("com.mysql.jdbc.Driver");
    //2 获得连接
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/day05", "root", "1234");
    //3 创建Statement
    Statement st = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE);
    //4 书写sql
    String sql = "select * from t_user" ;
    //5 执行sql
    ResultSet rs = st.executeQuery(sql);
    //使用结果集 反向修改数据库
    rs.next();//将光标移动到第一行
    rs.updateString("name", "汤姆");// 修改第一行name列的值为中文汤姆
    rs.updateRow();// 确认修改
    //6关闭资源
   st.close();
   conn.close();
  }
}