Programmer Think

Welcome to the MySQL technical articles shared by the great SQL community. If you have any questions or want to learn, you can leave a message in the comment area below. After seeing it, you will answer itIn the MGR test, after artificially creating the disk full problem, the node is OO m killedProblem descriptionIn MySQL 8.0 26 vs GreatSQL 8.0 ...

Relational structured storage has some disadvantages, because it needs to define all columns and their corresponding types in advance. However, in the process of business development, it may be necessary to expand the description function of a single column. At this time, if the JSON data type can be used well, the boundary between the storage ...

Chapter 6 SQL aggregate function JSON_ARRAYAGG An aggregate function that creates an array of JSON formatted values. Note: IRIS is available, and previous versions of IRIS are not available. outline JSON_ARRAYAGG([ALL | DISTINCT [BY(col-list)]] string-expr [%FOREACH(col-list)] [%AFTERHAVING]) parameter ALL - optional - specify JSON_A ...

About NoSQL overview 1, Development of NoSQL 1. Stand alone MySQL Era In the 1990s, the number of visits to a website was generally not too large, and a single database was enough. With the increase of users, the website has the following problems: When the data volume increases to a certain extent, the stand-alone database cannot be put do ...

Basic operation of JDBC In order to reuse the code and improve the development efficiency, it is very necessary to design the addition, deletion, modification and query of JDBC database. JDBC data operation steps are generally divided into the following five steps: 1, Load database driver class Class.forName("com.mysql.cj.jdbc.Driver"); ...

Function 1. Functional overview Use Python to complete a program to add or delete student information about MySQL database, mainly involving knowledge points: cursor use, SQL statements, and the basic knowledge previously learned. 2. Mind Mapping The idea has been put into practice 2. Start Practice Pre-war preparation You need to f ...

Transaction: understanding is a processing unit. This processing unit may contain deleted and modified operations that need to be processed. It is necessary to ensure that the processing unit is successfully completed or not executed at all. Transaction characteristics: atomicity, consistency, isolation and persistence Transactions are divide ...

Note: the official document of superset does not support Windows system. I started to use windows, and there was an error in the configuration thumbnail later. OS: Ubuntu20.04 Superset: 1.3.2 This is the problem I encountered in the installation and the information collected through query. The solutions to some problems may not be suitab ...

I brief introduction MyCat is an open source distributed database system and a server that implements MySQL protocol. Front end users can regard it as a database agent and access it with MySQL client tools and command line, while its back end can communicate with multiple MySQL servers using MySQL native protocol or with most mainstream databa ...

[the most complete MySQL summary in history] MySQL super detailed notes This article mainly introduces what MySQL is, its classification, SQL commands, MySQL installation precautions, classification and common commands in MySQL, Including: data query (basic query, sort query, condition query, time query, string query, aggregate function, gr ...