JDBC

1. 使用jdbc步骤
          a.导入数据库厂商提供的驱动程序（导入jar包）
          b.加载驱动程序
             Class.forName("驱动程序")
          c.获得连接
             Connection conn = DriverManager.getConnection（url，username，password）；
             url = “jdbc：数据库：//ip地址：端口；数据库”；
             username：“用户名”；
             password：“密码”
          d.获得执行sql对象，执行sql返回结果
            Statement stat = conn.createStatement();
     ResultSet rs = stat.executeQuery(sql语句);
          e.处理结果集
             while（rs.next）{
                    Xxxx s =rs.getXxxx（“字段名|数字”）
                    }
            注意：数字下标从1开始
          f.释放资源
             rs.close();
      stat.close();
      conn.close();

package day28;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Collection;

public class TestJDBC {

    

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //1.加载驱动
        try {
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //2.获得连接 url =jdbc: sqlserver://localhost:1433;DatabaseName = schoolDB
        //username,passwprd
        //jdbc:数据库：//IP地址：端口号数据库名
        try {
            Connection conn = DriverManager.getConnection
                    ("jdbc:sqlserver://localhost:1433;DatabaseName = MySchool","sa","sa");
            System.out.println(conn);
            //3.执行sql语句，得到返回结果
            String sql = "select * from emp";
            //获得执行sql语句的对象
            Statement stat = conn.createStatement();
            ResultSet rs = stat.executeQuery(sql);
            //4.处理结果(游标，迭代指针)
            while(rs.next()){
                int empno = rs.getInt("empno");
                String ename = rs.getString("ename");
                System.out.println(empno+ename);
                
            }
            //5.释放资源
            rs.close();
            stat.close();
            conn.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }  
        
        
}

 

2 . PreparedStatement比Statement提高了代码的可读性和可维护性，
            提高了SQL语句执行的性能，提高了安全性
3.   核心API
               DriverManager          ：管理驱动
               Connection             ：数据库连接
               Statement              ：执行sql语句
               PreparedStatement      ：执行sql语句
               execute（）；          ：执行任何的sql
               executeQuery （）；    ：执行查询sql
               executeUpdate  （）；  ：执行增删改sql
            ResultSet

package day28;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class TestJDBC2 {

    public static void main(String[] args) {
        try {
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            String url ="jdbc:sqlserver://localhost:1433;databaseName = epet";
            String username = "sa";
            String password = "sa";
            
            Connection conn = DriverManager.getConnection(url,username,password);
            
            int id = 1;
            String name = "刘春雷";
            String money = "200";
            String sql = "insert into master(id,name,money) values(?,?,?)";
            PreparedStatement pst = conn.prepareStatement(sql);
            pst.setInt(1, id);
            pst.setString(2, name);
            pst.setString(3, money);
            pst.executeUpdate();
            id = 2;
            name = "韩蝶儿";
            money = "500";
            pst.setInt(1, id);
            pst.setString(2, name);
            pst.setString(3, money);
            pst.executeUpdate();
            id = 3;
            name = "程亚南";
            money = "100";
            pst.setInt(1, id);
            pst.setString(2, name);
            pst.setString(3, money);
            pst.executeUpdate();
            pst.close();
            conn.close();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}