Case Statement In Select Oracle

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...

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 ...

When it comes to big data, it has to do with Alibaba. The world's leading E-commerce enterprise, the amount of data processed every day is unmatched by any other company, it is also transforming into a real data company--mysql is an important weapon in the transformation of Alibaba. 　　A database architect who interviewed Ali, who believes Ali has the best performance of open source MySQL, beyond any relational database and NoSQL. In the 2009, Oracle acquired the copyright of MySQL by acquiring Sun, and the industry began to question the use of Oracle ...

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 ...

With the popularity of the Internet and the continuous development of network technology, the confidentiality requirements of data are more and more high. In the usual server/client mode mis development, because the program to maintain the connection with the database server, for the flexibility and extensibility of the program, the join parameters (user ID and login password) can not be written in the program death (in fact, writing death is not a good way), There are two kinds of general methods: one is to store the join parameters in the registry, and the other is to read the INI file directly. And the safety of several methods are not very good, give people the opportunity. Myself...

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: ...

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 ...

The intermediary transaction SEO diagnose Taobao guest Cloud host technology Hall recently to do a campus website, today summary and finishing related experience, so the so-called "whim", spend some time to write an article, hope to be able to communicate with you new people, get the support of webmaster friends. The number of Chinese universities is huge, the number of people, according to a variety of survey data show that the domestic university students ideological exchange is a large part of their own university BBS, which fully illustrates the importance of university Campus forum, and a good university forum how to build it? Accordingly I according to own experience and experiences, comprehensive ...