• Why SQL Server2008 order by cannot be used directly in the union clause


    According to the requirements, each takes top 20. Since it is random, SQL Server order by newid() is used, and then all the data are unionized. So I immediately gave the answer: select top 20 * from xxx where type=1 order by newid()    union    select top 20 * from xxx where type=0 order by newid()   But the SQL query analyzer is wrong and the syntax is wrong. At first […]

  • Android studio 4.1 released to enhance the development experience in all aspects


    We’re happy to release itAndroid Studio 4.1Stable version, for you to bring a series of common editing, debugging and optimization functions. One of the key appeals of version 4.1 is to help you useAndroid JetpackLibrary (i.e. Android development library suite) follows best practices and improves code writing efficiency. Based on your feedback, we have directly […]

  • How is one of the SQL query statements executed in MySQL infrastructure?


    preface As an excellent relational open source database, MySQL database is favored by everyone. In our daily work, we often deal with it. Do you know how MySQL is executed when we write SQL? Let’s talk about it. MySQL architecture withselect * from T where ID=10;Take this SQL statement as an example:When we execute the […]

  • Android | teaches you how to develop a smile grabbing artifact on Android in 30 minutes


    preface Some time ago, Richard Yu introduced Huawei HMS core 4.0 to you at the press conference. To review the information of the conference, please stamp:What does Huawei mean by releasing HMS core 4.0 globally? Among them, there is a key service introduced, machine learning kit (mlkit). What can machine learning service do? What problems […]

  • Simple analysis of MySQL architecture


        The figure above is the simple architecture diagram of MySQL, which gives you a general concept. I will make further analysis for you. Connector: When connecting to the MySQL database, you will be waiting for the MySQL serverConnector;The responsibility of the connector is to establish the connection with the client, obtain the authority, […]

  • How to close Android studio Analyzer? Android studio’s skills of closing analyzer


    Android studio profiler (Android analyzer) is used to analyze the current Android CPU, memory, network and so on. Many novices only minimize the analyzer but do not close it after using it, which results in high computer memory consumption. So, how do you turn off the parser? Let’s take a look at the detailed graphic […]

  • SQL analysis of distributed | dble


    Author: Lu LuTechnical people who love technology and are willing to share are mainly engaged in the research of database related technology.Source: original contribution*The original content is not allowed to be used without authorization. Please contact the editor and indicate the source. What is the difference between database middleware and database? In my opinion, in […]

  • asp.net Core Series 75 elasticsearch and Chinese word segmentation configuration


    1、 Elasticsearch on Windows 1. Download address:     https://www.elastic.co/cn/downloads/elasticsearch If the browser downloads files slowly, it is recommended to use Thunderbolt to download files quickly. Download version 7.5.2 2. Modify the configuration file After downloading, extract and find config\ jvm.options In principle, allocate 50% of the total memory to elastic search, but not more than 30.5gb, […]

  • ZEEK extract file


    First, reference Official document file analysis 2、 Explanation of terms FAF, file analysis frameworkDPD, dynamic protocol detection Three, text 1. Document translation In the past, it was very troublesome to write ZEEK scripts to analyze the contents of files, because according to the network protocol involved in file transfer, there may be many different events […]

  • The difference of two-step permission check in MySQL execution


    Original link: he Xiaodong blog The article comes from a question of lemonVersion 8.0 of the document reference in the article Screenshot of the problem: The main test scenario is: the K field does not exist, and there is no select permission. See which error is thrown first, and the result is that the error […]

  • Nine Java performance debugging tools, at least one is required


    Nine Java performance debugging tools, what are better and more tools, welcome to add. NetBeans Profiler _ NetBeans profiler can be found in NetBeans. The NetBeans analyzer is an extension of NetBeans to provide analysis capabilities for the NetBeans ide. NetBeans IDE is an open source integrated development environment. The NetBeans ide supports the development […]

  • MYSQL Actual Warfare-1. Basic Architecture of Mysql


      1. Mysql can be divided into server layer and storage engine 1.1 server layer: Connectors, query caches, analyzers, optimizers, executors, including all built-in functions (date, time, mathematics, encryption functions), all functions across storage engines are in this layer, such as stored procedures, triggers, views, etc. 1.1.1 connector: Responsible for establishing connections with clients, obtaining […]