Built in object creation event

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Added by GoncaloF on Fri, 11 Feb 2022 17:30:24 +0200

MyBatis learning: advanced query (one-to-one mapping)

1, One to one mapping Suppose that in the permission system, a user can only have one role, that is, the relationship between users and roles is limited to one-to-one relationship. 1.1 handling one-to-one relationships using automatic mapping A user has a role. We add the role class SysRole field in the user class SysUser. As follows: publi ...

Added by djelica on Fri, 11 Feb 2022 09:45:56 +0200

Summary of sub queries used in MySQL

1. Classification of sub query 1.1. Non associated subquery Subquery statements can be executed separately without reference to any content in the included statement. It is called non associated subquery. 1.1.1. Single row single column subquery The subquery statement returns a single row and single column table. This type of subque ...

Added by veveu on Thu, 10 Feb 2022 15:28:48 +0200

Deployment of pure domestic environment (Galaxy Kirin + Feiteng) JAVA program (Springboot + Mybatis + Damon database)

JAVA program deployment preface Operating environment: Galaxy Kirin + Feiteng CPU Project framework: Springboot + Mybatis + Dameng database jdk1 eight The last one wrote the source code of the project, and this one mainly wrote the deployment of the project on the domestic operating system and the installation and creation of Dameng data ...

Added by Pezmc on Wed, 09 Feb 2022 21:50:13 +0200

Explain and index best practice

1, Explain tool introduction Use the EXPLAIN keyword to simulate the optimizer to execute SQL statements and analyze the performance bottlenecks of your query statements or structures Add the explain keyword before the select statement. MySQL will set a flag on the query. Executing the query will return the information of the execution plan i ...

Added by cyanblue on Wed, 09 Feb 2022 17:59:09 +0200

MySQL special system induction and quick start (common cmd commands, common function summary, SQL statement elaboration with examples) is suitable for beginners and quick check of usage

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Added by westen on Wed, 09 Feb 2022 12:54:03 +0200

Install and deploy MGR cluster | explain MGR in simple terms

The original content of GreatSQL community cannot be used without authorization. Please contact Xiaobian and indicate the source for reprint.[toc]This paper introduces how to use GreatSQL 8.0.25 to build a three node MGR cluster.1. Installation PreparationPrepare the following three servers:IPportrole172.16.16.103306mgr1172.16.16.113306mgr2172. ...

Added by sparrrow on Tue, 08 Feb 2022 19:10:28 +0200

[leetcode SQL daily practice] - 595 Big country

   🎈 Write in front 🙋‍♂️ Hello everyone, I'm super dream. You can call me Xiaomeng~ We all know that we have to deal with the database almost every day, whether in study or daily work. In order to better operate the database, our SQL knowledge reserve is essential. If you want to master SQL well, you must practice and stu ...

Added by Slippy on Tue, 08 Feb 2022 08:20:18 +0200

Basic skills of SQL -- complex query

Previously reviewed: SQL knowledge points -- insert records SQL knowledge points -- update records and delete records Basic skills of SQL (I) -- SQL and database Basic skills of SQL (II) -- basic query Basic skills of SQL (III) -- aggregation and sorting catalogue view Advantages of view Delete view Subquery scalar subquery ...

Added by Jude on Mon, 07 Feb 2022 02:13:36 +0200

[The road to java learning] (mysql article) 002.mysql grouping query and join query

Single Line Processing Function Data processing functions are also known as one-line processing functions Features of one-line processing functions: one input corresponds to one output. As opposed to single-line processing functions, multiline processing functions. (Multi-line processing function features: multiple inputs, corresponding to o ...

Added by edmore on Sun, 06 Feb 2022 19:17:52 +0200