SEARCH KEYWORD -- COMMAND LINE


  Select top 3 values from each group in a table with SQL

Yesterday, my friend Liu Bing asked me a question about how to select top 3 values for each person in a database table using SQL. I think this question is interesting and it deserves some thoughts. Here I record down how to solve this issue. Assume we have a table which has two columns, one column contains the names of some people and the other column contains some values related to each person. One person can have more than one value. Each value has a numeric type. The question is we want to se...

   SQL,Correlated query,top 3     2013-05-23 03:21:25

  About C++ comma operator precedence

When learning programming language, we will always have one topic about the operator precedence. Since there are many operators can be used in one expression, there should be some rules regarding which operation can happen first so that the compiler or interpreter can handle them correctly. One rule of programming with expression is using as much as brackets as you can to avoid unexpected results. Here we refer one problem we see online about the comma operator in C++. The following program has ...

   comma,precedence     2012-11-12 10:25:00

  7 Ways Tablets are Better than Laptops or Smartphones

Imagine a situation of preparing for a short weekend trip to a smaller village or a countryside with beautiful nature, fresh air and breathtaking scenery, where your cousins are eagerly expecting you for their twentieth marriage anniversary; you seem to be almost ready, but one thing is missing!  A considerable amount of work is still ahead of you, and you also want to stay in touch with your friends, which makes it a bit difficult to decide whether it would be more suitable to take your l...

   TABLETS,SMARTPHONE,LAPTOP     2018-07-25 05:32:44

  Different types of keystore in Java -- Windows-MY

Windows-MY is a type of keystore on Windows which is managed by the Windows operating system. It stores the user keys and certificates which can be used to perform cryptographic operations such as signature verification, data encryption etc. Since it's a kind of native keystore, Java doesn't have a general API to access it. To help Java applications access the keys and certificates stored in Windows-MY keystore, Java provides a separate API -- SunMSCAPI. The SunMSCAPI provider is ...

   JAVA,KEYSTORE,WINDOWS-MY,SUNMSCAPI     2016-01-09 05:45:59

  Server monitoring shell scripts

There are many open source server monitoring software such as cacti and nagios. Besides these, can we write our own shell scripts to monitor them? The shell scripts written by ourselves can fulfill our special requirements better and have a more detailed coverage. Below are some commonly used shell scripts used by Evangelist, an Oracle DBA. 1. Check network gateway traffic #!/bin/bash #network #Mike.Xu while : ; do time='date +%m"-"%d" "%k":"%M' day='date +%m"-"%d' rx_before='...

   Server monitor,CPU,memory,shell     2013-08-30 21:56:14

  What is the Right Length of a Blog Article?

The length of your blog posts can build your website or break it. If you thought that this is a myth then you are wrong. Pleasing the search engines is one of the targets of SEO efforts. However, you have to please your visitors as well. With good traffic then you will get good ranking on the Search Engine Results pages (SERPs). One of the best ways to increase your traffic is to make sure that once a visitor lands on your site then they will come again for more information. The length of your b...

   DIGITAL MARKETER ,SEO,SEO TOOLS     2016-03-05 04:18:28

  Writing Java codes conforming to coding standard

Recently, I was doing some cleanup to one of my current Java project. I find there are many codes which are not conforming to the Java coding standard. So I list them here and hope that people can improve your codes and write maintainable codes. Format source code and manage imports in Eclipse Eclipse provides functions of auto-formatting and imports management, you can use following shortcuts to use these functions. Ctrl+Shift+F --> Format source code Ctrl+Shift+O -- Manage imports an...

   Java, Code standard,Style     2012-09-18 12:50:28

  Different types of keystore in Java -- JKS

JKS is Java Keystore, a proprietary keystore type designed for Java. It can be used to store private keys and certificates used for SSL communication, it cannot store secret keys however. The keytool shipped with JDKs cannot extract private keys stored on JKS. This type of keystore usually has an extension of jks. Next we will show how to operate the JKS keystore with pure Java code. Create JKS keystore The simplest method to create a JKS keystore to create an empty keystore. We can first get an...

   DEMO,EXAMPLE,KEYSTORE,JKS     2014-09-05 20:21:51

  About browser event

First look at following codes: var $ = KISSY.all; $(‘a’).on(‘click’,function(e){ doSomeThing();//This function seems very famous e.halt(); }); The above codes seem complete the work we want them. The browser will not redirect us to the link in href, but is there some issue with the codes above? Before explaining what's wrong with the above codes, we first need to understand some concepts. Browser default behavior When we click a link, the browser will redirect us to anoth...

   JavaScript event,Event bubbling,event capturing     2012-11-15 11:15:41

  How to choose a jQuery plug-in?

jQuery plug-in provides a good way to save time and simplify the development, programmers don't need to write each component from scratch. However, the plug-in will also be a destabilizing factor in your code library. A plug-in saves countless development time, but a poor quality plug-in will cost more than the actual time to write your own component from scratch. Luckily, usually you have many pls to choose from, but even if you have only one plug-in, you also need to know whether it's worth us...

   jQuery, plug-in     2012-10-27 03:51:40

RECENT