Day34 database (a) Introduction to the database, MySQL installation and basic grammar mysql installation, start-up and basic configuration - windows version

1. Database

What is the data (Data)

　　Data records of a transaction descriptor is, the symbol described things may be numbers, text, images, etc., to be described in a computer object, it is necessary to extract the characteristics of things, the composition of one record.

What is the database (DataBase, referred to as DB)

　　The database is stored data warehouses, but now the warehouse is on a computer storage device, stored in a certain format

　　Data in the database has a smaller redundancy, higher data independence and extensibility line

What is a database management system (Database Management System, referred to as DBMS)

　　Database management system is an application to manage data and databases

Database management database is divided into two categories:

　　Relational Database

　　　　And it is linked between the restriction data and

　　　　The first step needed to determine the structure of the table when the table is usually a relational database structure, so we use this type of database

　　　　Common relational databases have: MySQL, Oracle, sqlite, db2, sql server

　　Non-relational databases

　　　　Data are usually stored in the form of k, v keys

　　　　Common are: Redis, MongoDB (document database, very close relationship type of non-relational databases), memcache

Note: In the development of our Python, the most commonly used is the MySQL database

 

 

2. acquaintance MySQL

　　MySQL is a relational database management system, developed by the Swedish company MySQL AB, currently part of  Oracle  's products. MySQL is one of the most popular relational database management system, WEB applications, MySQL is the best RDBMS (Relational Database Management System, a relational database management system) applications.

　　MySQL is a relational database management systems, relational database stores data in separate tables rather than putting all the data in a large warehouse, thus increasing the speed and improved flexibility.

　　MySQL SQL language used is the most common standardized language used to access databases. MySQL software uses a dual licensing policy, divided communities and commercial versions, due to their small size, high speed, low cost of ownership, especially open source this feature, the development of small and medium websites have chosen MySQL as the database website.

Content classification data in MySQL database

　　First, a database library consisting of different sizes, and a library of different-sized tables, a table consists of records of different sizes make up

Our internal database can be likened to a computer file system 
library    >>>    folder 
list    >>>    file 
records >>>    data in the file line by line, called a section of the record 

header: the first row of the table 

: Field Name + field type

　

3.MySQL download and install

mysql installation package provide open source operating system on each of us, including ios, linux, windows.

mysql installation, start-up and basic configuration - linux version  (https://www.cnblogs.com/Eva-J/articles/9664401.html)

mysql installation, start-up and basic configuration - mac version  (https://www.cnblogs.com/Eva-J/articles/9664401.html)

mysql installation, start-up and basic configuration - windows version  (https://www.cnblogs.com/Eva-J/articles/9669675.html)

 

4. Using MySQL small operation before

　　MySQL is a c socket-based communication / s software architecture, so he also has server and client, the server startup program is mysqld bin folder, start the client program is mysql bin folder

　　The best will be added before running the MySQL bin directory to the system environment variables, so that we can open the program directly

　　First, we use the Administrator cmd to open the terminal

　　Server open: direct input mysqld

　　Open Client: cmd reopen a terminal window, enter mysql -h 127.0.0.1 -p 3306 -uroot -p, if the local IP and port number may be omitted

　　Exit the client: exit or quit

　　View all databases: show databases

　　View a process: After exiting the terminal database input tasklist | findstr + Name

　　Kill a process: taskkill / F / PID + process ID

Note: 1.MySQL when there is no initial login password, you can directly enter,

　　 2.MySQL sql statement, is a semicolon, the semicolon does not knock no losers default, the client will continue to let us enter

Production environment variable
　　to the path where the startup files added to the system environment variables in

　　Note: Once you've configured a while to restart the mysql server and terminal cmd

Mysqld will be made into a system service
　　to make your system service must be the administrator cmd terminal

　　mysqld --install

Change password
　　without a password
　　　　mysqladmin -uroot -p password 123
　　the password case
　　　　mysqladmin -uroot -p123 password 123456

　　When the error command input can be used when \ c cancel the previous command cancel

Crack the code
　　first service has been launched end stopped

　　1. The user name and password to skip verification of the server function is activated
　　　　mysqld --skip-grant-tables skip start the server authorization table
　　2. modify the administrator password corresponding to the user
　　　　update mysql.user set password = password (123 ) where user = 'the root' and Host = 'localhost';
　　3. the server again to close the current username and password verification as to start
　　4. in the normal manner username and password server connected mysql

Profiles
　　\ s View mysql server simple configuration
　　suffix configuration files are usually ini end

　　mysql do not modify the configuration file that comes with
　　it you can create a configuration file my.ini
　　mysql server will automatically load the configuration in your configuration file in the startup my.ini

　　Need to first stop the server is restarted after changing the configuration file to take effect

　　Modify the configuration file must restart the server

 

Basic operation within 4.MySQL

1 . Operation folder (Library) 
   by: create database db1 charset utf8; 
   search: show databases; check all 
　　　　show create database db1; check single 
   change: alter database db1 charset latin1; modified encoding 
   deleted: drop database db1; deletion library


 2 . operation file (table) 
   to switch to the next folder: use db1; specify the library 
　　　　　　　　　　　select database (); View current library of 
   increase: create table t1 (id int, name char); 
   check: show tables; see below in a library All tables 
　　　　show create table t1; view information single table 
　　　　desc t1; description See table 
   changes: ALTER table T1 Modify name char ( . 3 ); 
      ALTER table T1 change name NAME1 char ( 2 ); 
   deleted: drop table T1;
    

 . 3 . contents file operation (recording) 
   by: insert into t1 values (. 1, ' egon1 ' ), (2, ' egon2 ' ), (. 3, ' egon3 ' ); can be inserted into a plurality of 
   check: SELECT * from T1; Search field information 
　　　　select name from t1; Search fields specifying information 
　　　　select name from t1 where id = 1 ; query information field with filter conditions 
   change: Update T1 SET name = ' SB ' WHERE ID = 2 ; a modified data information field, which can be modified 
   to delete: Delete from T1 WHERE ID = 1 ; delete the specified condition data 
　　　　delete from t1; delete all the data in the table 

   empty table: 
       the delete from T1; # if there is increment id, the new data is still the same as before they were removed as the last start.
       truncate table t1; large amount of data, delete a speed faster than, and directly from scratch,

 * AUTO_INCREMENT represents: the self-energizing
 * primary key represents: constraint (repeats not and can not be empty); Find the acceleration