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Optimization of a query You should encounter this scenario. A self incrementing primary key is set in MySQL, but some data is subsequently deleted, resulting in discontinuous primary keys. You can use the following command to query those discontinuous primary keys. -- Writing method 1 select id from (select id from Table name order by id asc ...

Dual machine hot standby scheme Kept + MySQL master-slave replication to realize active and standby 1.1 deployment mode The two servers deploy the same running environment and services. The running environment includes java running environment, redis, mysql, kept and java background services 1.2 realization effect When the background process of ...

MySQL DQL statement DQL is the data query language of MySQL Query all columns SELECT * FROM Table name; Query specified column SELECT Column 1 [, Column 2, ... column N] FROM Table name; Completely duplicate records only once As like as two peas of the query result, the one row is displayed. Generally, this is rarely the case when querying ...

1, Flyway introduction demo address Flyway Is an open source database version management tool. It can be easily used on the command line or introduced in Java applications to manage our database version. In a project or product, it is difficult to clarify the business and design the database table at the beginning, so the data table will con ...

mysql service 1 1. Summarize the common storage engines and characteristics of mysql. show engines; View database engines supported by the database MyISAM engine features: Transaction not supportedRead and write are mutually exclusive and cannot be read or written at the same timeForeign keys are not supportedRead and write data faster an ...

Note: this blog is MySql table operation instruction 1. If you want to learn the basic MySql instructions, you can use the author Blog Learning; If you want to practice further, you can do it after learning Operation 2 After that, according to Blog MySql instance Practice! Add, delete, query and modify ~ simple instructions Create table ...

This article is mainly aimed at the addition, deletion, modification and query of MySQL and upgrading again. If you want to see the basic additions, deletions and changes, you can see the previous article of the blogger. Here, the blogger posts a link for you: https://blog.csdn.net/weixin_53033446/article/details/119005596?spm=1001.2014.3001.55 ...

Centos7 completely uninstalls MySQL & installs & starts Uninstall section 1. See what mysql has installed rpm -qa |grep -i mysql 2. Start the uninstallation, and execute the installed XXX in sequence: yum remove XXX 3. Check to see if the uninstall is complete rpm -qa |grep -i mysql 4. Find mysql related directory find / -na ...

Author: Hu ChengqingMember of aikesheng DBA team, good at fault analysis and performance optimization, personal blog: https://www.jianshu.com/u/a95... , welcome to the discussion.Source: original contribution*It is produced by aikesheng open source community. The original content cannot be used without authorization. For reprint, please contact ...

Author: Yu ZhenxingAikesheng is a member of DBA team and is keen on technology sharing and writing technical documents.Source: original contribution*It is produced by aikesheng open source community. The original content cannot be used without authorization. For reprint, please contact Xiaobian and indicate the source.background information Due ...