Concurrent programming: how to use locks in java?

The depth of Java lock When multiple requests operate the database at the same time, first change the order status to paid, and add 200 to the amount, which will cause duplicate notifications under the concurrent scenario query condition. SQL: Update Pessimistic lock and optimistic lock Pessimistic ...

Posted on Mon, 22 Jun 2020 01:44:27 -0400 by CantonWeb

Web05 mybatis advanced (using annotation development and SQL to build objects)

MyBatis advanced Today, I'd like to share with you the following Annotation implementation single table development Annotation for multi table operation SQL construction statement of MyBatis Here are some key words of MyBatis annotation development Annotation implementation single table developme ...

Posted on Sun, 21 Jun 2020 04:30:55 -0400 by dad00

MyBatis Series Part 5: MyBatis cache

  1. What is MyBatis caching? Using MyBatis cache can reduce the number of interaction between java application and database. From this point of view, its benefits are the same as using MyBatis to delay loading, which can improve the running efficiency of the program to a certain extent. For exampl ...

Posted on Sun, 21 Jun 2020 02:58:54 -0400 by springo

Spring Boot+Element files are uploaded synchronously with form upload files

Business logic needs to add records first and then generate corresponding unique file names by adding the IDS returned by the sql operations of records. el-upload does not automatically upload some pits described below <el-upload :action="uploadUrl()" :on-remove="handleRemove" :before-upload="bef ...

Posted on Fri, 19 Jun 2020 22:45:00 -0400 by revraz

Mybatis plus paging query return pit

    Paging query of mybatis plus, You need to pass in, page (paging condition), and Wrapper query condition to return an IPage, which should be known to all those who have used it Note that looking down, I'll replace the incoming paging page object with the same one, Page page = new Page(1, 3); Qu ...

Posted on Thu, 18 Jun 2020 23:48:37 -0400 by Placebo

Understanding some of the concepts of search, aggregation in Elasticsearch through kibana

1. Corresponding entity in Java public class Person { String name; int age; } 2. Data in kibana { "_index": "person_index", "_type": "person_type", "_id": "i674x3IBsOhWggMeikEo", "_score": 1, "_source": { "age": 9, "name": "L ...

Posted on Thu, 18 Jun 2020 12:13:46 -0400 by huzefahusain

Springboot+layui + code generation full set of forked

1. Objectives 2. Organization structure, user, role and authority sorting 2.1. Users and roles 2.2. Function point, role, menu, role function authorization, role data authorization 2.3. Role data authorization 2.3.1. Role data authorization (page configuration) 2.3.1.1. Only view yourself - abnor ...

Posted on Thu, 18 Jun 2020 03:50:16 -0400 by otuatail

NumPy advanced tutorial - super detailed

Article catalog Numpy basic tutorial link 1, Inside the target of darray 1.1 Numpy dtype hierarchy 2, High order array operation 2.1 reshaping array 2.2 C order and Fortran order 2.3 join and separate arrays 2.31 stacking assistant: r_ And c_ 2.4 repeating elements: tile and repeat 2.5 the equivalen ...

Posted on Tue, 16 Jun 2020 02:33:01 -0400 by badboy1245

What is data definition language (DDL) in MySQL series?

If you are just learning about MySQL, please read the following articles before you read this article. Some knowledge may be a little difficult for you to master, but please believe me, according to the learning process I provide, you can read it again and again, so that you won't know where to start wh ...

Posted on Tue, 16 Jun 2020 02:03:50 -0400 by rmelino

My development diary

Today, I mainly did the basic data management of the test user module, and encountered a relatively large problem. The user attributes are all IDS, but they need to be converted to the corresponding string type when returned to the front end, and then there are various kinds of validation of non mandatory parameters. A complex SQL, especially i ...

Posted on Tue, 16 Jun 2020 00:46:03 -0400 by RynMan