Case When Exists 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...

In "2013 Zhongguancun Big Data Day" Big Data Wisdom City Forum, cloud Human Science and Technology CEO Wu Zhuhua brings to the theme "about intelligent city thinking-real-time large data processing opportunities and challenges" speech. He believes that the opportunities for large data in various industries are as follows: Financial securities (high-frequency transactions, quantitative transactions), telecommunications services (support systems, unified tents, business intelligence), Energy (Power plant power grid Monitoring, information collection and analysis of electricity), Internet and electricity business (user behavior analysis, commodity model analysis, credit analysis), other industries such as Intelligent city, Internet of things. Wu Zhuhua ...

I joined the LinkedIn company at an exciting time six years ago. From that point on, we cracked down on a single, centralized database and started switching to a special distributed System suite. This is an exciting thing: the Distributed graphics database, the distributed search backend, the Hadoop installation, and the first and second generation key value data stores that we build, deploy, and still run until today. The most rewarding thing we've learned from all of this is that the core of many of the things we build contains a simple idea: log. Sometimes ...

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 ...

I joined the LinkedIn company at an exciting time six years ago. From that point on, we cracked down on a single, centralized database and started switching to a special distributed System suite. This is an exciting thing: the Distributed graphics database, the distributed search backend, the Hadoop installation, and the first and second generation key value data stores that we build, deploy, and still run until today. The most rewarding thing we've learned from all of this is that the core of many of the things we build contains a simple idea: log. Sometimes ...

The logical design of database is a very broad problem. In this paper, the main key design of the table is discussed in the design of MS SQL Server, and the corresponding solutions are given. Primary key design status and problems about database table primary key design, in general, based on business requirements, based on business logic, the formation of primary key. For example, when sales to record sales, generally need two tables, one is the summary description of the sales list, records such as sales number, the total amount of a class of cases, and the other table record of each commodity ...

Now, talking about big data is not new, all walks of life are competing in the excavation of large data "great value", resulting in a wide variety of customized large data programs. On the other hand, there are large groups of "double-edged swords" that hold large data at risk. Is big data a business opportunity or a crisis? If you have to choose, I think it is business opportunities, and any business opportunities are risk factors, the risk need not blindly expand to sensational. If everyone can obtain success from the big data, then the benefit is the social overall progress, but will not change the social individual or the group's strength pattern. I think, do ...

With the help of cloud computing, China's information industry will gain an opportunity to upgrade from "Made in China" to "create in China".  But for most small and medium-sized enterprises, how to break the information island and realize the internal data circulation is a more realistic problem. "Although China's rapid economic development, but some enterprises within the lack of IT support, creating bottlenecks." "China's globalization, breaking the island of information, needs customization," said Bill Humphrey, Pervasive international market and global customer service Director of the US data integration platform manufacturer.

The scalability of the system is the main reason for promoting the development of NoSQL movement, including distributed system coordination, failover, resource management and many other features. That makes NoSQL sound like a big basket that can be stuffed with anything. Although the NoSQL movement does not bring fundamental technological changes to distributed data processing, it still leads to extensive research and practice on protocols and algorithms. It is through these attempts to gradually summarize some effective database construction methods. In this article, I will focus on the NoSQL database distributed special ...