Basic knowledge of database

One 、 Common databases

1、 Relational database Relational database ： The official interpretation of relational databases is difficult to understand , In fact, to put it simply , A relational database is an organizational structure that stores data in the form of rows and columns , This is a two-dimensional table , And there may be some relationships between multiple tables .

1)Oracle Oracle Is the U.S. oracle company （ Oracle ） It provides a set of software products with distributed database as the core ,oracle The characteristic of database is security 、 High speed 、 Stable 、 Good concurrency , These characteristics make many large enterprises choose the database without hesitation oracle. In the early years , The world 500 Strong almost 100% All are oracle Users of . however oracle Is the charge , And it's not cheap , This also makes many start-ups or small and medium-sized enterprises completely unable to afford the expenses , Instead of using oracle, Turn to easy to use , More lightweight, free and open source MySQL.

2)MySQL MySQL Is a source code development of relational database management system , And because of its speed , Reliability and applicability are favored by small and medium-sized enterprises . Although previous versions didn't support thing manipulation 、 Subquery 、 Foreign keys 、 Stored procedures and views . But from 02 Published in 4.0beta Since Edition ,MySQL For external use innoDB As the default engine , The ability to process things and cache data is greatly improved ,05 Year of 5.0 Version has added stored procedures 、 Server cursor 、 trigger 、 Query optimization and distributed things function .

3)MariaDB MariaDB The database is MySQL A branch of , Maintained by the open source community , Development MariaDB Part of the reason is because of concerns about Oracle's acquisition MySQL after , There will be generals MySQL The intention of closing the source , So the community USES branching to avoid this risk . MariaDB Fully compatible with MySQL, Include API And the command line , yes MySQL The perfect substitute for , Storage engine ,MariaDB It uses xtraDB Replaced the MySQL Of InnoDB.

4)Sqlserver Sqlserver By Microsoft Development and promotion of the database , It was originally created by Microsoft、Sybase and Ashton-tate Developed by three companies , And in 1988 The first OS/2 edition . Ms SQL server Mainly for small and medium enterprises . Its biggest advantage is that it integrates Ms All kinds of products and resources of the company , Provides a powerful visual interface 、 Highly integrated management development tools , Building business intelligence quickly （BI） We have made a lot of achievements in this respect .

2、 Non relational database Non relational database ： The data structure of non relational database is completely different from that of relational database , It mainly stores data in the form of key value pairs .

1)Memcached Memcached In order to livejournal its Danga Interactive The company's Brad Fitzpatric A software developed first , It is a good solution to a series of database bottlenecks , Because in web Frequently in application , Centralized access to the database , It will bring a series of problems caused by high concurrency . For example, it will increase the burden of database 、 The response deteriorated 、 Website display delay and other significant impact on these issues , And with memcached Data caching mechanism provided , These problems are not problems .

2)Redis Redis It's a key-value The storage system . and memcached similar , It supports storage value There are more types , Include string（ character string ）、list（ Linked list ）、set（ aggregate ）、 and hash（ Hash type ） etc. .Redis Is a high-performance key-value database . Redis Appearance , A lot of compensation memcached This kind of key/value Lack of storage , In some cases, it can play a very good complementary role to the relational database .

3)MongoDB MongoDB Is a product between relational and non-relational databases , Non-relational databases are the most versatile , Most like a relational database . The data structure he supports is very loose , Is similar to json Of bson Format , Therefore, courses store more complex database types . Mongo The biggest feature is that the query language he supports is very powerful , Its syntax is somewhat similar to that of an object-oriented query language , Almost all of them can realize most of the functions similar to relational database form query , It also supports indexing the database .

3、 ... and 、 How to learn database

1） establish / Delete Library 、 establish / Delete table 、 View Library 、 See the table

2） Backup 、 Restore data .

3） stored procedure 、 View

4） Import 、 Derived data

5） Database basic configuration ： Change Password 、 Add users, etc

6） Database linking tool ： Such as WorkBench Navicat phpMyAdmin etc.

7） Basic additions and deletions sentence

8） A little more complicated SQL ： Multi-table query 、 Subquery wait

9） At least know the common databases ：Mysql MSSQL Oracle Memcached Redis Mongodb

10） Database installation 、 Deploy ： At least you have to install a database on your own server or computer Interface test and interface document generation tool ：apipost

Two 、 Why study databases

It can react on business and quickly analyze positioning problems There are many problems in software development , After all, it's just a matter of data in a database , For example, we need to verify the registration source , If we don't go to the library , I didn't know this field existed , Although it says so in the demand , But actually when I do a functional test from the page , I can't see whether the registration source is right or not , So we're going to look at the database .

Apipost The official link ：https://console.apipost.cn/register?utm_source=10009