Mysql Querying

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 ...

Open source data is divided into two factions, NoSQL enthusiasts like to publish a lengthy criticism of relational database limitations, MySQL enthusiasts stubbornly defend the health relational database-insist that the data neatly stored in the table. 　　You'd think the two sides would never get along, but in fact, tens of thousands of companies have been trying to combine relational and relational databases, and have tried it many years ago. But the development of new technologies is often antithetical to the technology of the past. When NoSQL developed, the name of the light sounded like ...

It is well known that query optimization is an unavoidable topic in any database. For database engineers, optimization is the most challenging job. MySQL Open source database is no exception. In fact, the author believes that the database optimization is not as much as we imagine the suffering. 　　Under normal circumstances, you can start from the following four details to do a good job in the MySQL database query optimization. First, use the Explain keyword to evaluate the flaw in the query statement as shown in the following figure, now the author in the database to execute a simple select ...

Mysql Guide sql distinct delete duplicate records How to use distinct keyword in mysql Filter the result list in a select statement Duplicate value If you want to delete duplicate data query data, you can use the distinct keyword to filter duplicate values, the following distinct usage. select distinct column_name from table_name; Let's take a look at a simple example ...

Data encryption and decryption are very important in the security field. For programmers, storing user passwords in ciphertext in a database is important to intruders who plagiarize users ' privacy. There are a variety of front-end encryption algorithm can be used for data encryption, decryption, I recommend a simple database-level data encryption, decryption solution. Take the MySQL database as an example, it built the corresponding cryptographic functions (Aes_encrypt ()) and decryption functions (Aes_decrypt ()). Inserts encrypted data into the table insert in ...

Dbkiss is a database browsing tool made up of a single PHP file that supports MySQL and PostgreSQL databases, supports the import and export of data, can search the entire database or a single table, and provides an advanced SQL Editor, template retention, Multiple queries perform functions at the same time. Dbkiss is a one-file PHP database browser which is easy to upload and use. It su ...

Today's world is a large data age of the information world, our life, whether life, work, learning are inseparable from the support of information systems. The database is the place behind the information system for saving and processing the final result. 　　Therefore, the database system becomes particularly important, which means that if the database is facing problems, it means that the entire application system will also face challenges, resulting in serious losses and consequences. Now the word "Big Data age" has become very popular, although it is unclear how the concept landed. But what is certain is that as the internet of things 、...

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When querying data, we often need to specify a few rows of data to be returned. As now there is a B/s architecture application, each page may display only 30 records. In order to improve the efficiency of the display, the database is generally required to return only 30 records at a time. When the user presses the next page, return 30 records from the database, and so on. This can shorten the time that the data is displayed. This is very effective when the base table for the query is larger. You can use the Limit keyword to implement this requirement at this time. The limit clause can be used to force a SELECT query statement to return ...

Hive is what is in contact with a new thing the first thing to go back to is: What is this? Here is an introduction to the Hive Wiki: Hive is a data warehouse infrastructure built in top of Hadoop. IT provides tools to enable easy data ETL, a mechanism into put businessesflat-out ...