• Analysis of scan of redis command


    Grape Command syntax Command meaning: Incrementally iterates a collection element. Command format: SCAN cursor [MATCH pattern] [COUNT count] Command actual combat: Basic execution traversal redis> scan 0 1) “17” 2) 1) “key:12” 2) “key:8” 3) “key:4” 4) “key:14” 5) “key:16” 6) “key:17” 7) “key:15” 8) “key:10” 9) “key:3” 10) “key:7” 11) “key:1” redis> […]

  • A quick introduction to Linux system


    Introduction to Linux system 1. What is OS Special_ Software_ , up can directly control the hardware, downward can support QQ such program operation. 2. Common operating systems Win7 win10 MAC Android IOS Symbian Linux 3. Development history of operating system Before 1965, computers were not popular, only in military or research institutions. A mainframe […]

  • Mybatis avoid stream query


    preface When the specified query data is too large, we generally use paging query, page by page to put the data into memory processing. However, in some cases, it is not necessary to query data by paging. If all the data is loaded into memory at once, oom may occur. At this point, we can […]

  • [Mr. Zhao Qiang] using cursors in mongodb


    1、 What is a cursor? Cursor is a method of processing data. In order to view or process data in result set, cursor provides the ability to browse data forward or backward one or more rows at a time in result set. A cursor is actually a mechanism that can extract one record at a […]

  • Using MySQL in Python — basic use of pymysql


    The use of pymysql install sudo pip3 install pymysql Basic use from pymysql import connect #1. Create a link coon = connect() “”” *Parameter host: the connected MySQL host, if the local host is’ localhost ‘ *Parameter port: the port of the connected MySQL host. The default is 3306 *Parameter user: user name of the […]

  • VIM use and arrangement


    Delete operation dwDelete from cursor to end of wordd$Delete from cursor to end of linedd Delete entire row Display cursor position and file status:CTRL-g Jump to a specified line in the file:n+SHIFT-G n: Number, representing line number. If omitted, skip to the last line by default Find string:/ N find next / shift-n reverse / […]

  • Analysis of MySQL temporary table principle and creation method


    This article mainly introduces the principle of MySQL temporary table and the analysis of its creation method. In this article, the example code is introduced in detail, which has a certain reference learning value for your study or work. You can refer to the following for your friends MySQL can create a temporary table by […]

  • MySQL data section (8) — simple implementation of stored procedure


    Thinking: generally, our data is stored in the database, and the conventional CRUD operations are implemented by code, such as using PHP as a project, and all data processing needs to be implemented by active operation code. If we have a project now, the business needs to distribute the user’s order after the user places […]

  • MySQL data section (9) — the stored procedure implements the regular daily cleaning of expired data


    Requirement: there is an activity record form t_ Ad, every time a business initiates an activity, it will_ shake_ devices_ Some Association records are generated in the relation table. Now write a stored procedure implementation. If the activity expires, the data mark in the associated table will be deleted. 1. The code is as follows: […]

  • [VIM] automatically update modification time and times


    objective After each modification, you want to reflect the last modification time on the file header and update the modification times Main grammar submatch(n) Refer to the previous matching content, submatch (0) is all, submatch (1) is the first getpos(“.”) Get the current cursor positionsetpos(‘.’, save_ Cursor) to restore the location winsaveview() Save entire layout […]

  • Module import in JavaScript has one disadvantage


    Do you feel any discomfort when using the es2015 module import function? Anyway, I have! Let’s talk about it. 1. Name import and auto complete Suppose you write a simple JavaScript module: // stringUtils.js export function equalsIgnoreCase(string1, string2) { return string1.toLowerCase() === string2.toLowerCase(); } This is aStringutils module。 The module has a module namedequalsIgnoreCase, which […]

  • Linux – vim and file operation


    vim Edit file content – switch of three modes Last line mode : Q exit editing: W save text: WQ save and exit: q! Force exit :set nu displayLine No: set hlserch highlight: set nohlserch unhighlight /String full textsearch, from top to bottom? string full text search, bottom-upExample: / CFull text searchc $end of file: […]