PK a.k.a. Primary Key

How to create a wordpress widget control panel

2009-11-23T05:40:00.005+08:00

For my curiosity, I tried to create a simple Wordpress widget the other day to find out how it works. There is a ton of posts online to tutor you from scratch. Some of them are very clear and helpful. I recommend the following:

As for me, I tried to realize a widget with database activities, i.e. to create and drop tables, insert and update records. There is another one from Wordpress Codex which is ultimately helpful.

Creating Tables with Plugins

This post is in no place to substitute any of them listed above. However, when I was trying with my idea, everything works together well except that the code in the control panel method of my widget always gets executed twice! In terms of database, that is redundant data.

If you did follow those posts, your widget's control panel method will look like this:


//Control panel method
function control(){
//essential declaration
global $wpdb;
//set table name again
$table_name = $wpdb->prefix . "mytable";
//test if the form is submit,that is the save button clicked, get the arguments from the form
if ( isset($_POST['mywidget-submit'])){
 //some parameter transaction here

 //prepare query
 $insertsql='INSERT INTO '
  .$table_name
  .'(a,b,c,d,e)'
  .'VALUES'
  .'( A,B,C,D,E);';
  //execute query and write into database
  $wpdb->query( $insertsql );

 }

}
//design the control panel form here and output
$control_form=''.'...'
echo $control_form;
}

It is absolutely right and working. If you are just using add,update,delete_option (refer to the Wordpress functions) to manipulate your parameters. This is totally fine. In my case, the INSERT statement will be run twice every time the "Save" button is hit on the widget control panel.

Here is how it works:
When the "Save" button is pressed,the "hidden" input control in our control panel form is submitted and the whole is method is called. Now that we test the value from $_POST if the "hidden" control is submit and run the code to insert the Sql statement.

I suspect that when it is done, the control panel will be reloaded again by Wordpress however the $_POST['mywidget-submit'] status is never changed. That's why it happens twice every time.

My solution to this is simple (I believe this is not a perfect one. Let me know if you have others.) To explicitly unset the &_POST['mywidget-submit'] when the code is run, in this case, just after the Sql statement is issued.


//unset the post array otherwise the query is run twice
unset($_POST['mywidget-submit']);

Google Flu Trend 谷歌发布流感趋势实验站点

2009-04-30T17:08:00.006+08:00

Google发布了墨西哥的猪流感趋势警报:

http://www.google.org/flutrends/intl/en_mx/index.html

在这个站点上同时还透露了这个实验的细节, 工作原理, 甚至还有原始数据. 先挖个坑, 有空稍微看看.

Data Warehousing Maturity

2009-04-27T09:44:00.003+08:00

TDWI 's latest publication "Gauge Your Data Warehousing Maturity" presents six stage model for a typical BI system life cycle. It provides sort of guidance on where you are and where you should go in the process of BI/DW.

Sadly, I have found out the place I work is still sitting somewhere between prenatal and child stage--formatting reports and struggling with all kinds of spreadsheets. Users are not statisfied with what and how they get the data (althoug they are pretty satisfied with their own spreadsheets). One hand, information is bits here and bits there. On the other, it is not possible to "search" for the information as needed. Yet I find it very hard to push forward to the next stage as there seems to be little awareness that data is valuable asset in such an environment that real production only is treated as valuable.

The article clearly predicts in the end that at final stage of BI system, the system itself should become unnoticed. It is bit of ideal but I believed years ago that IT should not exist as its final form of existence.

译言的译文连接在这里!

短路SQL

2009-03-25T21:30:00.013+08:00

日前在考试时脑子短路了，搞的很低，回来想想发现傻的一比。今天有空赶紧写下来，靠靠靠靠靠。。。唉，鄙视自己一下。
1. having子句是用在group by前面还是后面。正解：后面。Where用来筛选分组前的记录，having用来筛选分组后的记录。
2.两张表(大概是这意思）：

T1.ID	T1.Value
1	a
2	b
3	c

T2.ID	T2.Value
2	a
3	b
4	c

写出以下三个查询的结果：

Select T1.value,T2.value from T1 LEFT JOIN T2 ON T1.ID=T2.ID；

结果：
a null
b a
c b

Select T1.value,T2.value from T1 LEFT JOIN T2 ON T1.ID=T2.ID where T1.ID=2；

结果：
b a

Select T1.value,T2.value from T1 LEFT JOIN T2 ON T1.ID=T2.ID and T1.ID=2；

结果：
a null
b a
c null

这下对了吧?

Windows Command 输出日期字符串

2009-03-20T22:02:00.001+08:00

昨天在写一个应用的备份的批处理命令，想要根据备份执行的日期来命名文件。作为一个很不入门的菜鸟，我已经连基本的MS-DOS命令都不怎么想的起来了。同事的脚本是用日期来建一个文件夹，然后把备份放在里面，我偏想直接用日期命名文件。搜了一下， CSDN上有个太监贴，同样的问题，最后没有结果。于是自己琢磨了一下，结果如下：

C:\>date/t
2009-03-20 星期五

C:\>echo %date:~0,4%%date:~5,2%%date:~8,2%
20090320

C:\>set var1=%date:~0,4%%date:~5,2%%date:~8,2%

C:\>set var1
var1=20090320

C:\>echo %var1%
20090320

C:\>echo %date:~0,4%%date:~5,2%%date:~8,2%%date:~11,3%
20090320星期五

当然，需要根据系统的日期格式进行调整。然后新建文件的时候只要把这个字符串再加上一些标识符，比如项目名称就可以每天有不重复的备份文件了。有些东西，知道了就很简单，不知道就很挫。好比，顺便还发现了Windows自己的makecab.exe程序的一些东西，挺好用的。关于makecab.exe能搜到很多，我就不贴了，提供别处搜不到的东西才是王道。

Tiny Tiny Little改动Blogger的Linklist, 让链接从新窗口打开

2009-02-04T17:14:00.000+08:00

1.
实在是一个小得不能再小的改进,也算是结束无所事事的过年.
打开Blogger的定制面板, 进入编辑HTML状态, 然后选上"Expand Widget Templates".
在Linklist这个wiget的地方可以找到如下的代码, 添加蓝色的部分便可.

<ul>
     <b:loop values='data:links' var='link'>
       <li><a expr:href='data:link.target' target='_blank'><data:link.name/></a></li>
     </b:loop>
   </ul>

2.
试验Gmail的引用格式发布出来是如何的样子.

这些是引用的句子.
另起一行

样式:<blockquotestyle="border: 1px solid rgb(222, 219, 222); padding: 10px; background-color: rgb(255, 193, 37); font-size: 15px; font-weight: lighter;"> This is quoted text</blockquote>

3.
推荐一首歌: Talk you down by The Script