import ctypes
from ctypes import *
dll=cdll.LoadLibrary('C:\xxx.dll')
floatAdd=dll.floatAdd      #加载函数对象
floatAdd.argtypes=[c_float,c_float]
floatAdd.restype=c_float
print floatAdd(1.4,3.45)

这要看order by的位置 一般讲order by是最后执行的 如果它在sql语句的最后面 ，有先于select执行的例子可以发出来 一起探讨一下

setData和getData在api中有好多同名的方法 你指的是哪一个？

public class server implements Runnable {// 服务端
static List socketList=new ArrayList();
// 读取 In
static Socket socket = null;
static ServerSocket serverSocket = null;
public server() {// 构造方法
try {
serverSocket = new ServerSocket(9999);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("****服务端*****");
server t = new server();
int count = 0;
while (true) {
try {
// System.out.println("端口9999等待被连接......");
socket = serverSocket.accept();
count++;
System.out.println("第" + count + "个客户已连接");
socketList.add(socket);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Print p = new Print(socket);
Thread read = new Thread(t);
Thread print = new Thread(p);
read.start();
print.start();
}
}
@Override
public void run() {
// 重写run方法
try {
Thread.sleep(1000);
BufferedReader in = new BufferedReader(new InputStreamReader(socket
.getInputStream()));
while (true) {
String jieshou = in.readLine();
System.out.println( jieshou);
for (int i = 0; i < socketList.size(); i++) {
Socket socket=socketList.get(i);
PrintWriter out = new PrintWriter(socket.getOutputStream());
if (socket!=this.socket) {
out.println(jieshou);
}else{
out.println("(你)"+jieshou);
}
out.flush();
}
}
} catch (Exception e) {

        e.printStackTrace();
    }
}

}
class Print implements Runnable {
static List socketList=new ArrayList();
Scanner input = new Scanner(System.in);
public Print(Socket s) {// 构造方法
try {
socketList.add(s);
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void run() {
try {
Thread.sleep(1000);
while (true) {
String msg = input.next();
for (int i = 0; i < socketList.size(); i++) {
Socket socket=socketList.get(i);
PrintWriter out = new PrintWriter(socket.getOutputStream());
// System.out.println("对客户端说：");
out.println("服务端说："+msg);
out.flush();
}
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
}
//client.java
package Socket;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;
public class client implements Runnable {// 客户端
static Socket socket = null;
Scanner input = new Scanner(System.in);
static String name=null;
public static void main(String[] args) {
int x=(int)(Math.random()*100);
client.name="client"+x;
System.out.println("****客户端"+x+"*****");
try {
socket = new Socket("127.0.0.1", 9999);
System.out.println("已经连上服务器了");
} catch (Exception e) {
e.printStackTrace();
}
client t = new client();
Read r = new Read(socket);
Thread print = new Thread(t);
Thread read = new Thread(r);
print.start();
read.start();
}
@Override
public void run() {
try {
Thread.sleep(1000);
PrintWriter out = new PrintWriter(socket.getOutputStream());
while (true) {
String msg = input.next();
out.println(name+"说:"+msg);
out.flush();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
class Read implements Runnable {
static Socket socket = null;
public Read(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
Thread.sleep(1000);
BufferedReader in = new BufferedReader(new InputStreamReader(socket
.getInputStream()));
while (true) {
System.out.println( in.readLine());
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
————————————————
原文链接：https://blog.csdn.net/qq_29606255/article/details/78679815

把整个命令贴一下

public static void main(String[] args) {
System.out.println("MySQL JDBC Example.");
Connection conn = null;
String url = "jdbc:mysql://...:3306/test?autoReconnect=true&useSSL=false";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "XXXXXXXX";
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName(driver);
conn = DriverManager.getConnection(url, userName, password);
stmt = conn.createStatement();
String sql = "select * from AAA";
rs = stmt.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("emp_id");
String name = rs.getString("name");
System.out.println("id = " + id + ", name = " + name);
}
// 关闭资源
rs.close();
stmt.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException sqlEx) { } // ignore
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException sqlEx) { } // ignore
}
}
}

不是一个东西 conda.exe是conda的环境启动 python.exe是启动python用的 这两个都没关系

gevent是第三方库，通过greenlet实现协程，其基本思路是：
当一个greenlet遇到IO操作时，就自动切换到其他的greenlet，等到IO操作完成，再在适当的时候切换回来继续执行。
asyncio是Python 3.4版本引入的标准库，直接内置了对异步IO的支持，不需要第三方的支持，
asyncio的编程模型就是一个消息循环。我们从asyncio模块中直接获取一个EventLoop的引用，然后把需要执行的协程扔到EventLoop中执行，就实现了异步IO。很多异步io操作这两个库都可以用，只是他们在不同场景下的效率和易用性可能有区别，当然这个得进行深入的测试和研究，单就现在普通的场景来说 区别并不大

setData和getData在api中有好多同名的方法 你指的是哪一个？

public static void main(String[] args) {
System.out.println("MySQL JDBC Example.");
Connection conn = null;
String url = "jdbc:mysql://...:3306/test?autoReconnect=true&useSSL=false";
String driver = "com.mysql.jdbc.Driver";
String userName = "root";
String password = "XXXXXXXX";
Statement stmt = null;
ResultSet rs = null;
try {
Class.forName(driver);
conn = DriverManager.getConnection(url, userName, password);
stmt = conn.createStatement();
String sql = "select * from AAA";
rs = stmt.executeQuery(sql);
while (rs.next()) {
int id = rs.getInt("emp_id");
String name = rs.getString("name");
System.out.println("id = " + id + ", name = " + name);
}
// 关闭资源
rs.close();
stmt.close();
conn.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException sqlEx) { } // ignore
}
if (stmt != null) {
try {
stmt.close();
} catch (SQLException sqlEx) { } // ignore
}
}
}

一般的情况是成员变量不用public修饰，可以增加专门的get 和set方法来访问成员变量

直接用均匀分布创建

其实本质是一样的 只是实现方式不一样 为什么呢？因为存储不一样，传统数据库只在一台或是几台机器上，机器之间的数据都是整块存储的 比如一个表就存在一个服务器上，所以查询sql的时候是直接提到内存查找，SQL-on-Hadoop解决的是数据表存在hadoop集群上，因为hadoop的块存储可能会使一个表跨多台服务器，那查表的时候要在多台服务器上查询，同时不同的sql查询的逻辑也不一样，这就需要一个分布式的sql引擎，这就是SQL-on-Hadoop的核心思想

datanode 数据块

啥地方写了 能发个地址或是截个图吗