Oracle Sql Select Case Example

We want to do not only write SQL, but also to do a good performance of the SQL, the following for the author to learn, extract, and summarized part of the information to share with you! (1) Select the most efficient table name order (valid only in the Rule-based optimizer): The ORACLE parser processes the table names in the FROM clause in Right-to-left order, and the last table in the FROM clause (the underlying table driving tables) is processed first, In the case where multiple tables are included in the FROM clause, you must select the table with the least number of records as the underlying table. If...

Intermediary transaction SEO diagnosis Taobao guest Cloud host Technology Hall log is a very broad concept in computer systems, and any program may output logs: Operating system kernel, various application servers, and so on. 　　The content, size and use of the log are different, it is difficult to generalize. The logs in the log processing method discussed in this article refer only to Web logs. There is no precise definition, which may include, but is not limited to, user access logs generated by various front-end Web servers--apache, LIGHTTPD, Tomcat, and ...

Storing them is a good choice when you need to work with a lot of data. An incredible discovery or future prediction will not come from unused data. Big data is a complex monster. Writing complex MapReduce programs in the Java programming language takes a lot of time, good resources and expertise, which is what most businesses don't have. 　　This is why building a database with tools such as Hive on Hadoop can be a powerful solution. Peter J Jamack is a ...

Intermediary transaction SEO diagnose Taobao guest Cloud host technology Lobby database optimization is a very complex task, because it ultimately requires a good understanding of system optimization. 　　Even though the system or application system does not know much about the optimization effect is good, but if you want to optimize the effect of better, then you need to know more about it. 1, the optimization of the system to run faster the most important factor is the basic design of the database. 　　And you have to be aware of what your system is going to do, and the bottlenecks that exist. The most common system bottlenecks are as follows: ...

Copyright Notice: Original works, allow reprint, reprint, please be sure to hyperlink form to indicate the original source of the article, author information and this statement. Otherwise, legal liability will be held. http://knightswarrior.blog.51cto.com/1792698/388907. First of all, the Templars are delighted to receive the attention and support of the cloud Computing series, which has been in preparation for several months, and finally released the first one today (because the article is too long, it is two pieces, and this is an article). In these months through constant making ...

This year, big data has become a topic in many companies. While there is no standard definition to explain what "big Data" is, Hadoop has become the de facto standard for dealing with large data. Almost all large software providers, including IBM, Oracle, SAP, and even Microsoft, use Hadoop. However, when you have decided to use Hadoop to handle large data, the first problem is how to start and what product to choose. You have a variety of options to install a version of Hadoop and achieve large data processing ...

This paper introduces how to build a network database application method by MySQL of the golden combination of Web database, PHP is a server-side embedded hypertext Processing language similar to Microsoft ASP, it is a powerful tool to build dynamic website. While MySQL is a lightweight SQL database server that runs on a variety of platforms, including Windows NT and Linux, and has a GPL version, MySQL is considered the best product for building a database-driven dynamic Web site. PHP, MySQL, and Apache are Linux ...

This paper is an excerpt from the book "The Authoritative Guide to Hadoop", published by Tsinghua University Press, which is the author of Tom White, the School of Data Science and engineering, East China Normal University. This book begins with the origins of Hadoop, and integrates theory and practice to introduce Hadoop as an ideal tool for high-performance processing of massive datasets. The book consists of 16 chapters, 3 appendices, covering topics including: Haddoop;mapreduce;hadoop Distributed file system; Hadoop I/O, MapReduce application Open ...

Editor's note: Jay Kreps, a chief engineer from LinkedIn, says that logs exist almost at the time of the computer's creation, and there is a wide range of uses in addition to distributed computing or abstract distributed computing models. In this paper, he describes the principles of the log and the use of the log as a separate service to achieve data integration, real-time data processing and distributed system design. Article content is very dry, worth learning. Here's the original: I joined the LinkedIn company at an exciting time six years ago. From that time ...

Editor's note: Jay Kreps, a chief engineer from LinkedIn, says that logs exist almost at the time of the computer's creation, and there is a wide range of uses in addition to distributed computing or abstract distributed computing models. In this paper, he describes the principles of the log and the use of the log as a separate service to achieve data integration, real-time data processing and distributed system design. Article content is very dry, worth learning. Here's the original: I joined the LinkedIn company at an exciting time six years ago. From that time ...