Literal meaning: a warehouse for storing data
Disadvantages of Excel:
1. Unable to manage a large amount of data (data above 10w)
2. Cannot operate the same data table concurrently
3. The database supports some advanced operations: grouping, connecting tables, etc.
There are constraints on the data type of each column, ID (integer), name (string), etc.
MySQL, SqlServer, oracle, sqlite, maridb, etc.
MySQL is used more, mainly for free
SqlServer from Microsoft, only used by universities and governments
oracle: Oracle, fees, financial companies (high security), Ali
sqlite: small file database, play with it yourself
maridb: Developed by one person with MySQL
memcache is not resolved
mongodb, a document database, does not use too much, and solves the problem of memory data loss after power failure
Redis: Used on Weibo to solve the problem of memory data loss after power failure
Use {"key":'value'} to store data
Relational database, store data in hard disk
Non-relational, store data in memory (fast speed)
Client and server similar to socket
Process:
1. The MySQL server is started first, listening on a specific port (3306)
2. The MySQL client connects to the server
3. The MySQL client can send operation commands to manipulate the data on the server.
Windows installation: go to the official website to find information (learning method) to install,
The official download address of MySQL software (https://dev.mysql.com/downloads/mysql/), I personally feel that downloading the compressed package version is better than downloading the installation package, because the default installation path of the installation package version is the system disk, and the entire database has About 1.8G, too much system disk storage.
1. Unzip
Decompress the database to which disk you want to install the database to (a separate folder)
2. Add environment variables
[Right-click on the computer]--"[Properties]--"[Advanced System Settings]--"[Advanced]--"(Win10 directly searches for environment variables to get to this step) [Environmental Variables]--"[In the second Find the line with the variable name Path in the content box, double-click] --> [Append the MySQL bin directory path to the variable value, use; split]
The mysql under bin is the client and mysqld is the server
3. Initialization
Enter mysqld --initialize-insecure on the cmd interface to initialize the database.
4. Start the MySQL service
Input: mysqld
5. Start the mysql client and connect to the mysql server
Enter the command: mysql -u root -p
6. Make mysql service into windows service
To make a MySQL Windows service, execute this command in the terminal:
"c:\mysql-5.7.16-winx64\bin\mysqld" --install
To remove the MySQL Windows service, execute this command in the terminal:
"c:\mysql-5.7.16-winx64\bin\mysqld" --remove
Note: The path in quotation marks is the mysqld path under the bin directory and must be an absolute path.
1. Start the service cmd and enter net start mysql
Stop the service cmd end enter net stop mysql
2. As shown in the figure below, manually start, stop, and restart the server in the computer management of the computer!
The above is the whole process of the 5.6 and 5.7 version installation.
After the above process is completed, the root permission password of the software is empty by default. When changing the password for the first time, enter the following command (in the cmd window, run cmd as an administrator, enter under cmd, not under mysql):
mysqladmin -uroot -p password "The password to be set"
To change the password for the second time and later, enter the following command
mysqladmin -uroot -p "original password" password "new password"
1 Shut down the running MySQL service. 2 Open a DOS window and go to the mysql\bin directory. 3 Type mysqld --skip-grant-tables and press Enter. --Skip-grant-tables means to skip the authorization table authentication when starting the MySQL service. 4 Open another DOS window (because the DOS window just now cannot be moved), and go to the mysql\bin directory. 5 Enter mysql and press Enter. If successful, the MySQL prompt> will appear. Connect to the authority database: use mysql;. 6 Change the password: update user set password=password("123") where user="root"; (don't forget to add a semicolon at the end). 7 Flush privileges (required steps): flush privileges;. 8 Exit quit. Log out of the system, enter again, and log in with the username root and the new password 123 just set.
1 Close the mysqld service 2 Execute in cmd: mysqld --skip-grant-tables = "You can log in without a password, bypassing the password verification authority 3 Execute in cmd: mysql =" mysql -uroot -p 4 Execute as follows sql command: (Special attention, version 5.7 here is different from 5.6) update mysql.user set authentication_string=password('') where user ='root';
5 flush privileges; (must be operated) 6 restart mysql service
View current user: select user();
The naming convention of the database:
Can be composed of letters, numbers, underscores, @, #, $, case sensitive, keywords such as create, select, etc. cannot be used, numbers cannot be used alone, and the longest cannot exceed 128 digits
Increase the create database database name charset utf8;
Delete the drop database database name;
Modified: Delete first and then add. If the database has data, a direct drop will cause the data in the database to be lost. In the online environment, the data cannot be deleted directly. You need to make a backup before deleting the data.
Check show databases;
Use database use database name;
Determine the currently used database: select database();
View all user permissions
select * from mysql.user\G;
View the permissions of a user
select * from mysql.db where user='user name'\G; User information is stored in a table named mysql.user
select user,password,host from mysql.user;