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Mybatis Plus custom IService and BaseMapper 1, Why did you study this thing Recently, I was independently responsible for the service R & D of a java module of innovative business in the company. When building the project, I chose Mybatis Plus to do the work of database Dao layer. Although it's not the first time I've contacted Mybatis Pl ...

preface In every business function, there is always a need to sort by time or by other fields. When we think of sorting, we will think of order by in MySQL. In the process of use, will there be unreasonable use, resulting in the decline of query speed? text To avoid full table queries, we usually add an index to the order by field, which is ...

catalogue 1, Introduction to mysql index 1. The concept of index 2. Basic principles of index creation 3. Index creation and classification 1. General index 2. Unique index 3. Primary key index 4. Combined index (single column index and multi column index) 5. Full text index (FULLTEXT) 4. View index 5. Delete index 2, Introduction t ...

preface: Previous articles have combed the whole process from front to back in terms of call structure. This article analyzes the whole process from the perspective of actual combat call. Before it was abstract, now it is actual combat. 1. Example code The code is the same as before. I'll post it here again 1.1 provider public class Pro ...

Answer #11: what is the difference between char and varchar in MySQL1. Experimental scenarioGreatSQL 8.0.25 InnoDB2. Experimental test2.1 differencesparametercharvarcharIs the length variableFixed lengthLengthenstorage capacity 0 ~ 2550 ~ 65,5352.2 construction test tableCREATE TABLE vc (v VARCHAR(4), c CHAR(4));2.3 test without exceeding the s ...

This note is the learning content of Alibaba cloud Tianchi Longzhu plan SQL training camp. The link is: https://tianchi.aliyun.com/specials/promotion/aicampsql preface This note is the learning content of Alibaba cloud Tianchi Longzhu plan SQL training camp. The link is: https://tianchi.aliyun.com/specials/promotion/aicampsql Dataset ...

Database installation Experimental environment Redhat8.3 Method 1: use the MySQL repository to install and deploy mysql 1, Add MySQL repository Add the MySQL Yum repository to the repository list of the system. This is a one-time operation that can be performed by installing the RPM provided by mysql. Follow these steps: Go to th ...

This paper describes how to use Canal to implement an asynchronous and decoupled architecture. Subsequent articles will be rewritten to analyze Canal principles and source code. Introduction to Canal Canal is the middleware used to get database changes. Fake yourself as a MySQL slave library, pull the master binlog and parse and process it. Pro ...

#Foreword The technologies used in the project related to this article: Layui, Mysql; In the project, you need to use a tree structure to display some data. It is found by consulting the relevant data of the tree view The tree view has strict requirements on the format of data, not only id, parent node and child node, but also the hierar ...

! Description: In the last 5 days, I have read the basic MySQL chapters of Master Kang of Shangxi Valley (forcing JVM) and shared some notes, mark, mark! 1. Subqueries A subquery is a query whose statement is nested within another query statementUse Attention Subqueries need to be enclosed in parenthesesPlace subqueries to the right of the ...