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SEARCH KEYWORD -- ORDER BY

  How MySQL optmizes ORDER BY

In some situations, MySQL will just use an index to fulfill the requirement of an ORDER BY or GROUP BY statement without extra sorting. Although ORDER BY will not have the exact match with index, index can still be used as long as the portion that is not included in the index is included in the where clause. The following queries will all use index to process the ORDER BY or GROUP BY part: SELECT * FROM t1 ORDER BY key_part1,key_part2,... ;SELECT * FROM t1 WHERE key_part1=constant ORDER BY key_p...

   MySQL,index,ORDER BY,optimization     2012-11-13 11:01:05

  Algorithm: Traverse binary tree

Preface There are three ways to traverse a binary tree based on the traversing order. Pre-Order: Root - Left - Right In-Order: Left - Root - Right Post-Order: Left - Right - Root Take below binary tree as example The node to be traversed in different order would be Pre-Order: A - B - C - D - E - F In-Order: C - B - D - A - E - F Post-Order: C - D - B - F - E - A Below are the implementations of different orders for traversing the binary tree. Pre-Order Traversing Recursive implementation N...

   ALGORITHM,BINARY TREE     2019-03-01 22:49:04

  Name resolution order in JavaScript

To understand what value a variable has in JavaScript, we need to understand some concepts such as scope and name resolution order. JavaScript has two scopes; one is program level and the other one is function level. Unlike in C,C++ or Java, JavaScript has no block level scope. So a variable defined in a if block will still be available outside. For example, the below example: var foo = 1; function bar() { if (true) { var foo = 10; } alert(foo); } bar(); The alert will display 10 since the ...

   JavaScript,Scope,Name resolution     2013-07-10 01:29:28

  SD Cards: Why Order Them In A Bulk?

Backing up important data is an undeniable aspect of the technologically advanced modern world. Be it photographs, videos, movies or other significant data, they all need to be stored properly for future use.  SD card or Secure Digital card is one such device that will help store all the relevant materials securely. As the name suggests, it secures all digital data. To understand why we should order bulk SD cards, we need to know why they are so beneficial.  They are extremely compact,...

   HARDWARE,SDCARD     2019-10-10 10:43:27

  ConcurrentHashMap vs Collections.synchronizedMap()

ConcurrentHashMap and Collections.synchronizedMap() both provide thread-safe operations of collections of data. They are used in multithreaded programs to provide both thread safety and performance improvements. In many cases, we can use either of them. But the realization of thread safety is different for these two implementations. ConcurrentHashMap will create an HashEntry[] array internally to store the elements passed in from a Map, while Collections.synchronizedMap() will return a Synchroni...

   ConcurrentHashMap,Collections.synchronizedMap     2014-09-18 05:04:59

  What are the Four Most Important Technologies Inside an Office, Today?

The office life has changed a lot since the beginning of the 21st century. Nowadays, technologies have taken over a large part of the work that people have to do, inside their walls. Some of them are more important than others, though. Here are four that no company should live without.  A VoIP Phone System If a company wants to communicate with its clients, it needs to install a centralized phone system. The old ones were complicated and costly. The more phone lines you had, the higher the ...

   SMARTPHONE,VOIP,5G     2022-12-24 06:35:02

  Sundar Pichai : Excited to try out iOS 7

Google Android business executives Sundar Pichai said on Twitter that he was excited to try out iOS7 beta and he would like to register as a Apple developer in order to experience iOS 7 early.The real reason why Sundar Pichai expresses interest on iOS 7 is not yet known, but at least "Know thyself, ever-victorious" is correct. Because as a person who is in charge of Android, he should grasp the status of competitors in order to know what the Android system can improve.However, Apple's iOS 7 appl...

   iOS 7,Google,Sundar Pichai     2013-06-12 00:57:30

  Windows 8 price is unveiled

Although it's still half month away from releases of Windows 8, Microsoft releases price of all versions of Windows 8 on Windowsteam blog. From now on, users can pre-order this product on Amazon, Bestbuy, Staples and Office Depot. The prices for different version : Windows 8 Professional Upgrade : $69.99 Windows 8 Pro Pack-Product Key Card : $69.99 Windows 8 64 bit(Full Version) -- OEM : $99.99 Windows 8 32 bit (Full Version) -- OEM : $99.99 Windows 8 Professional 32 bit (Full Version) -- OEM ...

   Windows 8, Price     2012-10-12 20:03:55

  iPhone 5 first weekend sales over 5 million

Within 24 hours openning for pre-order, 2 million iPhone 5 have been ordered, Apple announces that  sales of iPhone 5 are over 5 million in 3 days on sale., in addition, iOS devices upgraded to iOS6 are around 100 million. Apple CEO Tim Cook says : Demand for iPhone 5 has been incredible and we are working hard to get an iPhone 5 into the hands of every customer who wants one as quickly as possible,While we have sold out of our initial supply, stores continue to receive iPhone 5 shipments ...

   iPhone5,,iOS6,sale,pre-order     2012-09-24 10:55:12

  Binary tree iterator algorithm

Binary tree pre-order,in-order and post-order traversal are basics in algorithm and data structure.And the recursive binary tree traversal is a classical application of recursion. We define a binary tree node as : // C++ struct Node { int value; Node *left; Node *right; } In order binary tree traversal can be: // C++ void inorder_traverse(Node *node) { if (NULL != node->left) { inorder_traverse(node->left); } do_something(node); if (NULL != node->righ...

   Binary tree,Iterator,Traversal     2013-07-14 21:51:09

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