数据库查询

package JDBC;

import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Connection;
public class niuma {
public static void login( String username,String password) throws ClassNotFoundException, SQLException{
//1.注册驱动
Class.forName("com.mysql.cj.jdbc.Driver");
//2.获取链接
Connection conn= DriverManager.getConnection("jdbc:mysql://localhost:3306/zhengyu", "zhengyu", "180017");
//System.out.println("123");
//创建执行sql语句的对象
Statement stmt =conn.createStatement();
//4.书写一个sql语句
String sql="select * from c"
+ "ourse";
//5.执行sql语句
ResultSet rs=stmt.executeQuery(sql);
//6.对结果进行处理
while(rs.next())
{String teachername=rs.getString("teachername");
String classname=rs.getNString("classname");
String place=rs.getNString("place");
System.out.println(teachername+":"+classname+place);}

if(rs!=null)
{rs.close();}
if(stmt!=null)stmt.close();
if(conn!=null)conn.close();
}
public static void main(String[] args) {
try {
login("zhengyu","180017");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}