mysql eliminate duplicate rows

Sometimes a table or result set contains duplicate records. Sometimes it is allowed, but sometimes it needs to stop repeating records. Sometimes it needs to recognize that duplicate records are removed from the table. This chapter describes how to

Database Summarydisadvantages of traditional record data: Hard to save, backup difficult, inconvenient to finddatabase: A warehouse that stores data that describes the basic information of a transactionPros: 1. Persisting storage2. Very high reading

(Architecture and history)Mysql logical architectureIf you have a structural diagram of how Mysql components work together in your mind, this will help us understand the Mysql server.Mysql logical architectureThe upper-layer connection/thread

Original2016-08-12 Even Zhang Dbaplus community This article according to the Dbaplus community 69th period of the line to share organized, at the end of the book to send Oh ~Instructor Introductioneven ZhangData Development Engineer

Sometimes a table or result set contains duplicate records. Sometimes it is allowed, but sometimes it needs to stop repeating records. Sometimes it needs to recognize that duplicate records are removed from the table. This chapter describes how to

1. Why back up the database? Backup is the most important and easy to ignore for databases. Unexpected events may cause serious losses. The more important the data is, the more frequently the data changes, and the more frequently backup is

Sort mysql Databases and mysql DatabasesDatabase-related 1. InnoDB logs InnoDB has many logs. There are two concepts in logs that need to be clearly divided: Logical logs and physical logs. 1.1 logical logsThe operation information logs are

One, the connection databaseFormat: mysql-h host address-u user name-P user Password 1.1. Connect to MySQL on this computer. first open the DOS window, and then enter the directory Mysql\bin, and then type the command Mysql-u root-p, after the

20 basic optimizations and references for MySQL and 20 for MySQL Mysql has a wide range of performance optimizations:Index optimization, query optimization, query cache, server setting optimization, operating system and hardware optimization,

Database related 1. InnoDB's LogInnoDB has a lot of logs, and there are 2 concepts in the log that need to be clearly divided, logical logs and physical logs. 1.1 Logical logsThe information log about the operation becomes a logical log.For