MySQL不支持INTERSECT和MINUS，及其替代方法

Doing INTERSECT and MINUS in MySQL

By Carsten | October 3, 2005

Doing an INTERSECT

An INTERSECT is simply an inner join where we compare the tuples of one table with those of the other, and select those that appear in both while weeding out duplicates. So

SELECT member_id, name FROM a
INTERSECT
SELECT member_id, name FROM b

can simply be rewritten to

SELECT a.member_id, a.name
FROM a INNER JOIN b
USING (member_id, name)

Performing a MINUS
To transform the statement

SELECT member_id, name FROM a
MINUS
SELECT member_id, name FROM b

into something that MySQL can process, we can utilize subqueries (available from MySQL 4.1 onward). The easy-to-understand transformation is:

SELECT DISTINCT member_id, name
FROM a
WHERE (member_id, name) NOT IN
(SELECT member_id, name FROM table2);

Of course, to any long-time MySQL user, this is immediately obvious as the classical use-left-join-to-find-what-isn’t-in-the-other-table:

SELECT DISTINCT a.member_id, a.name
FROM a LEFT JOIN b USING (member_id, name)
WHERE b.member_id IS NULL

Reference:                                                     

1. http://blog.sina.com.cn/s/blog_4a9b80d00100b76s.html

Kill a Process by Process Name from Ubuntu Command Line

There are a number of ways to kill a process if you know the name of the process. Here’s a couple different ways you can accomplish this. We are going to assume that the process we are trying to kill is named irssi

    kill $(pgrep irssi)

    killall -v irssi

    pkill irssi

    kill `ps -ef | grep irssi | grep -v grep | awk ‘{print $2}’` 

These techniques can be useful in shell scripts, where you wouldn’t know the process ID and would need to restart or kill a process.

Reference:                                                      

1. http://www.howtogeek.com/howto/ubuntu/kill-a-process-by-process-name-from-ubuntu-command-line/

Simple php multiple processes

function fork()
{
$pid = pcntl_fork();
if ($pid === -1) {
// Error
echo 'Process could not be forked';
} else if ($pid) {
// Parent
echo 'pid of the child process:'.$pid."\n";
} else {
// Child
sleep(30);
}
}

fork();

How to run a php file in terminal

You can also create php scripts designed to run in the terminal like so:

# php -f php-file.php

1) Fire up a text editor and create your file, eg:

#!/usr/bin/php
// ^^ that line tells the command line that the file should be parsed by the php CLI interpreter
echo "Hello terminal\n";  

2) Give the script execute permissions:

# chmod +x script.php

3) Execute your script:

# ./script.php
Hello terminal

This is all assuming you have the CLI version of PHP. FC installs this by default.



Reference:                                                                                                      

1. http://www.linuxquestions.org/questions/linux-software-2/can-i-run-php-trom-terminal-435783/

Test code listing

// Comment

public class Testing {

public Testing() {

}

public void Method() {

/* Another Comment

on multiple lines */

int x = 9;

}

}

/**
     * SyntaxHighlighter
     */
    public class HelloWorld extends ActionSupport {
   private String name;
   private String message;

   public String getName() {
     return name;
   }

   public void setName(String name) {
     this.name = name;
   }

   public String getMessage() {
    return message;
   }
   
   public void setMessage(String message) {
    this.message = message;
   }
   
   public String execute() {
    setMessage("Hello, " + getName());
    return "SUCCESS";
   }

}

How to post well-formed code on Blogger ?

Syntax Highlighting with Blogger Engine

You can find a good solution here

All the brushes available

PDOStatement::execute(): SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens

Problem:

PDOStatement::execute(): SQLSTATE[HY093]: Invalid parameter number: number of bound variables does not match number of tokens


Reason:

The restrictions of PDO to the parameters bound are very strict, so you bind must exactly the same as that present in the query statement. No more parameter can be bound.

从今天起用这个博客来记录遇到问题及其的解决方案

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