20. Use and principle of PageHelper paging plug-in

1. Logical paging and physical paging Logical paging: also called memory paging. Logical paging depends on the code written by the programmer. What the database returns is not the paging result, but all the data, which is then passed by the programmer The code obtains the paging data, takes out all the data, first stores it in memory, ...

Posted by ChetUbetcha on Mon, 25 May 2020 20:53:31 -0700

(2)mysql -- query the Department with the largest number of people

sketch: Find out the Department with more than or equal to 10 people. main points On the basis of the previous article, we will examine the use of having. Previous link: http://blog.csdn.net/lovesummerforever/article/details/78806765 1. Function count() + group by. 2. having query. 3. The table structure and the a ...

Posted by NSH on Mon, 25 May 2020 08:12:30 -0700

Oracle learning - database operation

Oracle tables associated with users Each user needs to determine the table storage location, which is called table space In Oracle, table space is divided into two parts: permanent table space and temporary table space Temporary table space: when using SQL statement operation, the result enters the temporary table space first Persistent table ...

Posted by tobykw13 on Sun, 24 May 2020 20:14:59 -0700

SuperGridControl of C × WinForm dotnetbar control

1. Add header sgc.PrimaryGrid.SelectionGranularity = SelectionGranularity.Row;//Click to select a line DevComponents.DotNetBar.SuperGrid.GridColumn gc = null; gc = new DevComponents.DotNetBar.SuperGrid.GridColumn("ID"); sgc.PrimaryGrid.Columns.Add(gc); gc = new DevComponents.DotNetBar.Su ...

Posted by Cherry on Thu, 21 May 2020 07:17:50 -0700

DELETE_ DROP_ Research on record content of truncate command in binlog of ROW format

Today, a question suddenly comes to mind. Is the DELETE, DROP, TRUNCATE command the same as the binlog in ROW format? It's not the same to remember vaguely, but it's not sure; so let's take a look at the experiment. MySQL:5.6.20MySQL:5.7.22 1. View binlog settings mysql> show variables like 'binlog_format'; +---------------+-------+ | Vari ...

Posted by rharter on Wed, 20 May 2020 08:33:53 -0700

C#Data Operations Series - 10 NHibernate Trial

0. Preface In the last article, you basically completed the introductory tutorial for EF Core.Starting with this article, we'll try to explore more ORM frameworks on the.net core platform.So let's start with NHibernate. 1. Introduction to NHibernate NHibernate is the C#version of Hibernate, known as the pillar of ORM in Java (at least once).Hib ...

Posted by Josh18657 on Tue, 19 May 2020 18:04:34 -0700

Using Nginx to record and display the TOP 20 Web interface with slow response

I believe that many small partners have seen the response time and real-time display function of url interface in some commercial products. It can be understood that the slow query of web interface and the slow query of sql have the same magic, but if you want to do it, you have no way to start and don't know how to realize this function, so to ...

Posted by Jak on Mon, 18 May 2020 23:19:14 -0700

Integrating sharding JDBC to realize data desensitization in JPA project

introduction In the previous blog post, the database desensitization scenario and scheme have been completely introduced. The sharding JDBC open source project from Jingdong Digital Technology Co., Ltd. has realized this function transparently through the way of data source intermediate agent. However, although the function has been realized, ...

Posted by rocksolidsr on Mon, 18 May 2020 20:31:28 -0700

[java framework] JPA -- JPA mapping relationship

1. One way one to many configuration One way one to many is configured with the @ OneToMany tag. One party has a Set attribute associated with multiple parties. A Set can be a List or a Set, but the difference is that a List is ordered and a Set is not repeated. Corresponding to the configuration of @ OneToMany on one side: /** * One way one ...

Posted by scott.stephan on Mon, 18 May 2020 10:53:00 -0700

MyBatis Series Talking about SQL Execution Process Analysis

Catalog Use Mybatis on its own Mybatis Execution Process SqlSessionFactory\SqlSession MapperProxy Excutor Use Mybatis on its own This article focuses on analyzing the Mybatis framework's processes for executing SQL. Recalling that we used the Mybatis semi-automation framework on our own, we needed to follow t ...

Posted by BradZynda on Fri, 15 May 2020 17:17:44 -0700