Common Class 1, such as Object, String, Regular Expressions

1.object 1.equals Compare addresses, String overrides methods, and compares values. 2.toString Print object attribute information (class name and hexadecimal hascode) 3.hasCode The hash code value of the acquired object can be used as the identity card (unique identifier) of the current object in ...

Posted on Wed, 07 Aug 2019 02:46:41 -0700 by HA7E

MySQL 5.7 Multi-Instance Installation Configuration

1. Background description MySQL multi-instance concept Simply put, it is to open multiple different service ports (e.g. 3306, 3307) on a single server and run multiple MySQL service processes, which provide their services through different socket s listening on different service ports. b. MySQL multi-instance roles and problems Effective uti ...

Posted on Wed, 07 Aug 2019 01:44:24 -0700 by JunbinDuan

MYSQL transaction, isolation level, lock

Four Characteristics of Transaction When it comes to database transactions, yes, we first think of ACID, which is the four characteristics of transactions. A Atomicity C Consistency I Isolation D Persistence The problems brought about by it What problems will these four characteristics of transactions b ...

Posted on Tue, 06 Aug 2019 20:37:01 -0700 by cwiddowson

Introduction to SQL Server (SQL Statements)

Data type: char (fixed length) varchar (length varies with input) When the length of the string is fixed, use char because char is fast. nchar and nvarchar adopt Unicode coding on the basis of the former Unicode encoding is characterized by bytes and Chinese characters occupying the same space ah Bit (no need) int bigint floa t numeric (more ...

Posted on Mon, 05 Aug 2019 02:28:37 -0700 by sean72

Detailed explanation of MyBatis two-level caching mechanism

Caching is an important means to improve the performance of hardware and software systems; on the hardware level, modern advanced CPU s have three-level caching, and MyBatis also provides a caching mechanism, which can greatly improve our query performance. Level 1 cache Mybatis supports caching, but ...

Posted on Sun, 04 Aug 2019 22:43:38 -0700 by charlestide

Database System SSD7 Experiment 4 Trigger and Cursor

Experiment 4 Triggers and Cursors I. Experimental Purpose _Familiar with the method of database integrity control by SQL statement, understand the concept, definition method and trigger condition of trigger. Understand how cursors are defined, opened, used, closed and released. II. EXPERIMENTAL CO ...

Posted on Sun, 04 Aug 2019 05:08:35 -0700 by jkatcher

Linux Experiment 1 Common Commands and Shell Programming for Linux

Experiment 1 Linux Common Commands and Shell Programming I. Experimental Contents 1. Exercise a) When running the program on the command line, the Linux system searches a series of directories in the $PATH variable to find the corresponding files, writes a script to output all executable files in th ...

Posted on Sun, 04 Aug 2019 00:54:53 -0700 by importune

Introduction to egg.js

Links to the original text: https://www.cnblogs.com/rope/p/10859014.html What is Egg? Egg.js is an enterprise-level framework and application. It is hoped that Egg.js will breed more upper-level frameworks to help development teams and dev ...

Posted on Sat, 03 Aug 2019 03:58:01 -0700 by Residue

Hand-in-hand teaching you how to build standard systems with spring boot (2) -- multiple data sources

Define several issues: What is a standard system? Standard systems are the initial systems of system architects, including all the basic integration technologies of business systems, on which any application system can be developed. Technology used in standard systems and ultimate goals a. Using sp ...

Posted on Fri, 02 Aug 2019 02:05:35 -0700 by PHPnewby!

What is the ghost of MySQL binlog failing to recover data based on time?

Problem phenomena A customer feedback, when using binlog to do point-based recovery, often fails to correctly restore data (the probability is about 5%~10%). The database environment provides MySQL 5.7.27 version of cascade replication topology (A->B->C), main library A provides write ...

Posted on Thu, 01 Aug 2019 20:37:55 -0700 by dougp23