Compare addresses, String overrides methods, and compares values.
Print object attribute information (class name and hexadecimal 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
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
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
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
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
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
Experiment 1 Linux Common Commands and Shell Programming
I. Experimental Contents
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
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
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!
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