package query;

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Random;

import java.util.jar.Attributes.Name;

public class query {

    public static void main(String[] args) {

        // 驱动程序名

        String driver = "com.mysql.jdbc.Driver";

        // URL指向要访问的数据库名9million

        String url = "jdbc:mysql://127.0.0.1:3306/9million";

        // MySQL配置时的用户名

        String user = "root";

        // MySQL配置时的密码

        String password = "";

        try {

            // 加载驱动程序

            Class.forName(driver);

            // 连续数据库

            Connection conn = DriverManager.getConnection(url, user, password);

            if (!conn.isClosed())

                System.out.println("Succeeded connecting to the Database!");

            // statement用来执行SQL语句

            Statement statement = conn.createStatement();

            // 要执行的SQL语句

            for (int i= 0; i <= 9000 000; i ++){

                String rdname = randomString(8);

                int id = i;

                System.out.println(rdname);


//丢了引号会出错，找不到collumn“ID”或者“rdname”
int型的可以不用加，但是string类型的必须加。
有空研究下底层实现

                String sqll = "insert into testdata (id,name) values ('"+id+"','"+rdname+"')";

                statement.execute(sqll);

            }

            conn.close();

        } catch (ClassNotFoundException e) {

            System.out.println("Sorry,can`t find the Driver!");

            e.printStackTrace();

        } catch (SQLException e) {

            e.printStackTrace();

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

    /**

    * 产生随机字符串

    * */

    private static Random randGen = null;

    private static char[] letters = null;

    public static final String randomString(int length) {

        if (length < 1) {

        return null;

        }

        if (randGen == null) {

        randGen = new Random();

//        numbersAndLetters = ("0123456789abcdefghijklmnopqrstuvwxyz" +

//        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();

        letters = ("abcdefghijklmnopqrstuvwxyz").toCharArray();

        //numbersAndLetters = ("0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();

        }

        char [] randBuffer = new char[length];

        for (int i=0; i<randBuffer.length; i++) {

        randBuffer[i] = letters[randGen.nextInt(25)];

        //randBuffer[i] = numbersAndLetters[randGen.nextInt(35)];

        }

        return new String(randBuffer);

        }

}