Chapter 7 single line function
1. Understanding of function
1.1 what is a function
Function runs through the use of computer language. What is the role of function? It can encapsulate the code we often use and call it directly when necessary. This not only improves the code efficiency, but also improves the maintainability. In SQL, we can al ...
In the process of developing program system, we often need to consider the problem of system security,
Like this, it's like your database is running naked, isn't it? Maybe someone quietly deleted the database and let you run away? Therefore, the plaintext password cannot appear in the configuration file. Next, I will give you a detailed in ...
Added by minus4 on Thu, 24 Feb 2022 12:07:08 +0200
prefaceAfter reading the title, will you be surprised how Kunlun distributed database plays a distributed file system?Since version 0.9 of Kunlun distributed database requires the addition of HDFS distributed file backup function, my little brother will share the learning process in his work.HDFS (Hadoop distributed file system) is the core sub ...
Added by ih8telepathy.cm on Thu, 24 Feb 2022 11:31:54 +0200
FastAPI day 4
1. Multi application management
When we develop, a large number of routes are often involved. If all routes are written in one file, it is not conducive to us to modify a route and its processing function, and it is not conducive to the later maintenance and upgrading of the whole project. Moreover, the number of code lines ...
Added by webstyler on Thu, 24 Feb 2022 11:32:44 +0200
MySQL -- index creation principle
1. Data preparation
Create database and table
create database if not exists testindexdb;
create table student_info(
id int(11) not null auto_increment,
student_id int(11) not null ,
name varchar(20) default null,
course_id int not null ,
class_id int(11) defaul ...
Added by Sephiriz on Thu, 24 Feb 2022 11:23:00 +0200
prefaceThe previous article introduced the scenario of index invalidation( Talk about the failure of MySQL index ), the explain execution plan is used. The execution plan returns the information of each step in the execution process instead of executing it.Through the returned one or more rows of information, each part of the execution plan and ...
Added by desoto0311 on Thu, 24 Feb 2022 09:55:35 +0200
Basic Operation of Experiment 3 Database
(1) Create a database textbook:
CREATE database textbook
(2) Display and modify the maximum number of connections
show variables like "max_connections";
set global max connections = 8;
(3) Delete the database textbook
drop database textbook
Experiment 4 Definition and Mo ...
Added by blackcode on Wed, 23 Feb 2022 19:05:02 +0200
(1) Clone the table and generate the data records of the data table into a new table
1. Method 1: use like
create table test1 like info; #Using the LIKE method, copy the KY08 table structure to generate the test01 table
insert into test1 select * from info;
2. Method 2: direct cloning
CREATE TABLE test2 (SELECT * from info);
show cre ...
Added by Dada78 on Wed, 23 Feb 2022 14:36:47 +0200
Concept: constraints are rules that act on fields in a table and are used to limit the data stored in the table.Objective: to ensure the correctness, validity and integrity of the data in the database.classification ...
Added by FillePille on Wed, 23 Feb 2022 06:19:33 +0200