Summary of basic knowledge of MySQL database

xxxxxx 2020-11-07 16:43:51
summary basic knowledge mysql database


This paper deals with MySQL The basic knowledge of database is summarized and combed , The main contents are knowledge database 、 Common database rankings 、SQL And DDL Operating the database . I hope that after you read it , Be able to understand the concept of database , And be able to use SQL Statement operation database .

1、 Know the database

(1) How data is stored

a. Memory : Fast , But it can't be preserved forever , Data is temporary state .

b. file : Data can be stored permanently , But it's not convenient to manipulate the data , You need to query some data .

c. database : Data can be stored permanently , Fast query speed , The management of data is convenient , But it takes up resources , Need to buy .

(2) The concept of databases

A database is a warehouse for storing data , It's essentially a file system , Or in the form of files on the server computer . And all relational databases can use common SQL Statement Management .

2、 Common database rankings

a.MySQL: Open source free database , Small database , Has been Oracle Acquired .MySQL6.x The version also began to charge . later Sun The company acquired MySQL, and Sun The company was again Oracle Acquisition .

b.Oracle: A large database of charges ,Oracle Products of the company .

c.DB2:IBM The company's database products , Rechargeable . Often used in banking systems .

d.SQL Server:MicroSoft A database of medium-sized companies that charge .C#、.net Such language is often used .

e.SQLite: Embedded small database , It's used on the mobile phone , Such as :Android.

3、SQL The concept of

SQL(Structured Query Language) Chinese is also called structured query language . It is a query specification for all relational databases , Different databases support . As a general database operating language , It can be used in different databases . Different databases SQL There are some differences in sentences .

4、DDL Operating the database

(1) Create database

a. Create database directly db1

create database db1;

b. Judge whether it exists , If it doesn't exist, create the database db2

create database if not exists db2;

c. Create a database and specify the character set as gbk

create database db3 default character set gbk;

(2) view the database

Press tab Key can automatically complete the keyword

—— View all databases

show databases;

—— View the definition information of a database

show create database db3;

show create database db1;

(3) modify the database

Modify the default character set of the database

ALTER DATABASE Database name DEFAULT CHARACTER SET Character set ;

Specific operation :

take db3 The character set of the database is changed to utf8

alter database db3 character set utf8;

(4) Delete database

Delete database Syntax

DROP DATABASE Database name ;

Specific operation :

Each row SQL Statement needs to be selected for execution , Can press F9

Delete db2 database

drop database db2;

(5) Using a database

View the database in use

SELECT DATABASE(); One used mysql Global functions in

Use / Switch database

USE Database name ;

Specific operation :

—— View the database in use

select database();

—— Change the database to be used

use db4;

That's all MySQL Summarize and sort out the basic knowledge of database , Does everybody understand ? Zhengzhou men's gynecology hospital ranking list :http://news.39.net/ylzx/zztjyy/ Zhengzhou infertility hospital :http://yyk.39.net/zz3/zonghe/fc964.html

版权声明
本文为[xxxxxx]所创,转载请带上原文链接,感谢

  1. 【计算机网络 12(1),尚学堂马士兵Java视频教程
  2. 【程序猿历程,史上最全的Java面试题集锦在这里
  3. 【程序猿历程(1),Javaweb视频教程百度云
  4. Notes on MySQL 45 lectures (1-7)
  5. [computer network 12 (1), Shang Xuetang Ma soldier java video tutorial
  6. The most complete collection of Java interview questions in history is here
  7. [process of program ape (1), JavaWeb video tutorial, baidu cloud
  8. Notes on MySQL 45 lectures (1-7)
  9. 精进 Spring Boot 03:Spring Boot 的配置文件和配置管理,以及用三种方式读取配置文件
  10. Refined spring boot 03: spring boot configuration files and configuration management, and reading configuration files in three ways
  11. 精进 Spring Boot 03:Spring Boot 的配置文件和配置管理,以及用三种方式读取配置文件
  12. Refined spring boot 03: spring boot configuration files and configuration management, and reading configuration files in three ways
  13. 【递归,Java传智播客笔记
  14. [recursion, Java intelligence podcast notes
  15. [adhere to painting for 386 days] the beginning of spring of 24 solar terms
  16. K8S系列第八篇(Service、EndPoints以及高可用kubeadm部署)
  17. K8s Series Part 8 (service, endpoints and high availability kubeadm deployment)
  18. 【重识 HTML (3),350道Java面试真题分享
  19. 【重识 HTML (2),Java并发编程必会的多线程你竟然还不会
  20. 【重识 HTML (1),二本Java小菜鸟4面字节跳动被秒成渣渣
  21. [re recognize HTML (3) and share 350 real Java interview questions
  22. [re recognize HTML (2). Multithreading is a must for Java Concurrent Programming. How dare you not
  23. [re recognize HTML (1), two Java rookies' 4-sided bytes beat and become slag in seconds
  24. 造轮子系列之RPC 1:如何从零开始开发RPC框架
  25. RPC 1: how to develop RPC framework from scratch
  26. 造轮子系列之RPC 1:如何从零开始开发RPC框架
  27. RPC 1: how to develop RPC framework from scratch
  28. 一次性捋清楚吧,对乱糟糟的,Spring事务扩展机制
  29. 一文彻底弄懂如何选择抽象类还是接口,连续四年百度Java岗必问面试题
  30. Redis常用命令
  31. 一双拖鞋引发的血案,狂神说Java系列笔记
  32. 一、mysql基础安装
  33. 一位程序员的独白:尽管我一生坎坷,Java框架面试基础
  34. Clear it all at once. For the messy, spring transaction extension mechanism
  35. A thorough understanding of how to choose abstract classes or interfaces, baidu Java post must ask interview questions for four consecutive years
  36. Redis common commands
  37. A pair of slippers triggered the murder, crazy God said java series notes
  38. 1、 MySQL basic installation
  39. Monologue of a programmer: despite my ups and downs in my life, Java framework is the foundation of interview
  40. 【大厂面试】三面三问Spring循环依赖,请一定要把这篇看完(建议收藏)
  41. 一线互联网企业中,springboot入门项目
  42. 一篇文带你入门SSM框架Spring开发,帮你快速拿Offer
  43. 【面试资料】Java全集、微服务、大数据、数据结构与算法、机器学习知识最全总结,283页pdf
  44. 【leetcode刷题】24.数组中重复的数字——Java版
  45. 【leetcode刷题】23.对称二叉树——Java版
  46. 【leetcode刷题】22.二叉树的中序遍历——Java版
  47. 【leetcode刷题】21.三数之和——Java版
  48. 【leetcode刷题】20.最长回文子串——Java版
  49. 【leetcode刷题】19.回文链表——Java版
  50. 【leetcode刷题】18.反转链表——Java版
  51. 【leetcode刷题】17.相交链表——Java&python版
  52. 【leetcode刷题】16.环形链表——Java版
  53. 【leetcode刷题】15.汉明距离——Java版
  54. 【leetcode刷题】14.找到所有数组中消失的数字——Java版
  55. 【leetcode刷题】13.比特位计数——Java版
  56. oracle控制用户权限命令
  57. 三年Java开发,继阿里,鲁班二期Java架构师
  58. Oracle必须要启动的服务
  59. 万字长文!深入剖析HashMap,Java基础笔试题大全带答案
  60. 一问Kafka就心慌?我却凭着这份,图灵学院vip课程百度云