Create Index If Not Exists Mysql

As the most popular open source database, MySQL is widely used in Web applications and other small and medium-sized projects. However, in many large IT companies, MySQL has gradually deviated from the original open source version after being highly optimized and customized, more like a branch, such as the Webscalesql of Facebook, which was not long ago open source. 　　Recently, Mr. Xiong has published a blog post, from the perspective of large-scale web site architecture development of the changes in MySQL application, here for you to share. This article mainly describes the different and ...

If a computer manufacturer, its database holds machine and accessories product information. The table used to save the whole product information is called pc; the table used to save the parts supply information is called parts. There is a field in the pc table, used to describe the type of CPU used in this computer; there is a field in the parts table, the description of the CPU model, we can think of it as a list of all CPU models. Obviously, the CPU used by this manufacturer must be a model that exists in the supply information sheet. At this time, two tables ...

MySQL database sql statement commonly used optimization methods 1. Query optimization, should try to avoid full table scan, should first consider where and order by the columns involved in the establishment of the index. 2. Should be avoided in the where clause on the field null value judgment, otherwise it will cause the engine to abandon the use of indexes and full table scan, such as: select id from t where num is null You can set the default value of num 0, to ensure that Num column table does not null value ...

The complete collection of SQL statement operations deserves to be permanently stored the following statements are part of the MSSQL statement and are not available in Access. SQL classification: ddl-data Definition language (create,alter,drop,declare) dml-Data Manipulation Language (Select,delete,update,insert) dcl-Data Control Language (Grant,revoke, Commit,rollback first, briefly introduce the basic statement: 1, Description: Create number ...

There are a few things to explain about prismatic first. Their entrepreneurial team is small, consisting of just 4 computer scientists, three of them young Stanford and Dr. Berkeley. They are using wisdom to solve the problem of information overload, but these PhDs also act as programmers: developing Web sites, iOS programs, large data, and background programs for machine learning needs. The bright spot of the prismatic system architecture is to solve the problem of social media streaming in real time with machine learning. Because of the trade secret reason, he did not disclose their machine ...

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 ...

Intermediary transaction SEO diagnosis Taobao guest Cloud host Technology Hall 1, what is the directory submission? Everyone is familiar with the phone or directory Yellow pages. They contain a list of people or sorts of businesses in alphabetical order or by category. 　　Internet directories are basically the same, but they are known as web directories or online catalogs, and they are by category sites. In order for your site to be listed on these pages, you must first submit to the directory. If you do not submit your site directory differently, users will not be able to find your site unless they know what is due to an accident or input ...

"51CTO exclusive feature" 2010 should be remembered, because the SQL will die in the year. This year's relational database is on the go, and this year developers find that they don't need long, laborious construction columns or tables to store data. 2010 will be the starting year for a document database. Although the momentum has been going on for years, now is the age when more and more extensive document databases appear. From cloud-based Amazon to Google, a number of open-source tools, along with the birth of Couchdb and MongoDB. So what ...

Note: This article starts in CSDN, reprint please indicate the source. "Editor's note" in this article for the online Office platform Gleasy co-founder, technical team boss Shike wrote, he gave us to share the gleasy all the way to the technical combat. It is reported that the release of nearly three years of Gleasy, has successfully accumulated more than 50,000 enterprise users, in response to mass storage and high concurrency under the premise of a variety of basic problems in the solution of deep experience. At the same time, March 18, 2015, Gleasy will officially release the 3.0 edition "about", and the introduction of English version, complex ...