mysql的retrieve

package test;

import java.sql.*;

public class retrieve {
    public static void main(String[] args) {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

　　

        String sql="SELECT * FROM hero ";//查询整个表的数据，  select count(*) from hero  查询总数  select * from hero limit 0,5; 查询前五个数据

　　　　//降序：SELECT * FROM hero ORDER BY id DESC     升序：SELECT * FROM hero ORDER BY id ASC

/*
select * from tableName limit i,n
        # tableName：表名
        # i：为查询结果的索引值(默认从0开始)，当i=0时可省略i
        # n：为查询结果返回的数量
        # i与n之间使用英文逗号","隔开

        #
        limit n 等同于 limit 0,n
*/

   try (Connection c= DriverManager.getConnection("jdbc:mysql://localhost:3306/how2java?characterEncoding=utf-8",
                "root","123456");
             //创建语句
             PreparedStatement ps=c.prepareStatement(sql);){
            ResultSet rs=ps.executeQuery();
          while (rs.next()){
              int id=rs.getInt(1);
              String name=rs.getString(2);
              float hp=rs.getFloat(3);
              int damage=rs.getInt(4);
              System.out.println(name);
          }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}