1. Multi table query
1.1 many to one
(1) The first way is to query through linked list.
(2) The second way is through nested query. ---- two queries.
one point two One to many
2. Dynamic SQL
(1) if with where
(2) [choose when otherwise] and where
(3)set tag --- modify some fields ...
Posted by Pandolfo on Sun, 05 Dec 2021 16:15:44 -0800
Great! Someone introduced Ansible Playbook like this!
After a series of basic training and honing, it finally came to the application of relatively tall.
(Nani is just starting to review his future: https://blog.csdn.net/qq_41765918/category_11512932.html)
1. What is playbook
Chinese Name: script, which is an automatic processing script. P ...
Posted by Sassy34 on Sun, 05 Dec 2021 07:39:37 -0800
2.Internal sharing and Internet access
3.Port and ip mapping
1.Rule matching is performed from top to bottom
2.As long as it matches up, it doesn't match down
3.If no explicit rules are matched, the default rules will be matched (all are allowed by default and can be ...
Posted by mikeblaszczec on Fri, 03 Dec 2021 19:23:35 -0800
Today, let's take a look at how much faster the native executable built by Quarkus is than the Spring application, Ecological maturity is not discussed here .
Let's draw a conclusion and make a comparison with the Spring Web application with only one Controller.
Application start time: 0.012s vs 2.294s
Image size: ...
Posted by rm_phpbuilder on Fri, 03 Dec 2021 07:32:49 -0800
Transaction is one or more database operations that need to ensure atomicity, isolation, consistency and persistence at the same time
This article will explain the implementation methods of two transactions in springBoot, programming transaction configuration and declarative transaction configuration, as well as aspect transactions. O ...
Posted by Skyphoxx on Tue, 30 Nov 2021 13:34:46 -0800
1, Object description
Source code note: the Object class is the Root node of the hierarchical relationship of all classes. As the superclass of all classes, including arrays, it also implements the methods of this class. Note that what is said here is very clear, referring to the class level.
Therefore, there is a common saying in Java that e ...
Posted by d_barszczak on Mon, 29 Nov 2021 00:23:38 -0800
In the development and testing environment, we usually build a single instance of Redis to meet the development and testing requirements. However, in the production environment, if there are high requirements for availability and reliability, we need to introduce Redis cluster scheme. Although major cloud platforms now provide caching services ...
Posted by Ohio Guy on Sun, 28 Nov 2021 15:13:49 -0800
In daily development, there are always various interfaces. Front and rear end data transmission interfaces, third-party service platform interfaces. The front and rear data transmission interfaces of a platform generally communicate in the Intranet environment and use the security framework, so the security can be well protected. This article f ...
Posted by RobbertvanOs on Sun, 28 Nov 2021 05:18:49 -0800
This paper introduces how to use Canal to realize asynchronous and decoupled architecture. Later, I will write an article to analyze the principle and source code of Canal.Introduction to CanalCanal is a middleware used to obtain database changes.Disguise yourself as a MySQL slave database, pull the main database binlog, analyze and process it. ...
Posted by tinker on Fri, 26 Nov 2021 18:27:04 -0800
After nearly two years of optimization and polishing, Apache shardingsphere version 5.0.0 GA was finally officially released this month. Compared with version 4.1.1 GA, version 5.0.0 GA has been greatly optimized at the kernel level. Firstly, the kernel is completely transformed based on the pluggable architecture, and various functions in the ...
Posted by badproduce on Fri, 26 Nov 2021 16:29:36 -0800