MySQL (Database)

Database concepts:

A database is a warehouse that organizes, stores, and manages data in accordance with its data structure.
In real-world applications you will encounter a wide variety of databases such as NoSQL non-relational databases (MEMCACHED,REDIS,MANGODB), RDBMS relational databases (Oracle,mysql, etc.), and other databases such as HBase, which, in these databases, There will also be structured data, unstructured data, semi-structured data, and various data types listed below:

Structured data:
Can be represented by data or a uniform structure, which we call structured data, such as numbers, symbols. Traditional relational data model, row data, stored in the database, can be represented by a two-dimensional table structure.
Semi-structured data:
The so-called semi-structured data is the data between fully structured data (such as relational databases, data in object-oriented databases) and completely unstructured data (such as sound, image files, etc.), and XML, HTML documents are semi-structured data. It is generally self-describing, the structure and content of the data mixed together, there is no obvious distinction.
Unstructured data:
Unstructured database refers to a database whose field length is variable, and the records of each field can be made up of repeatable or non-repeatable sub-fields, which not only can deal with structured data (such as numbers, symbols, etc.) and is more suitable for processing unstructured data (full text, images, sounds, movies, hypermedia, etc.).
Unstructured data, including Office documents, text, images, XML, HTML, various reports, images and audio/video information in all formats, and more

Relational database:

relational database, which is based on relational model, uses mathematical concepts and methods such as set algebra to process data in a database.

MySQL management tool Navicat
Building a library: building a Database

MySQL management tool Navicat
Building a library: building a Database

MySQL management tool Navicat
Building a library: creating a data table

MySQL management tool Navicat
Fill in the field name: In general, the ID is set as the primary key

MySQL management tool Navicat
Fill in Field Name: Add field Name

MySQL management tool Navicat
Fill in Field name: Set FOREIGN key

A description of Structured Query language
Select * FROM table;
Select * from table where condition;
Select * FROM table where condition order by field order by ID Asc|desc;
Select field from table where Condition order by field order by ID Asc|desc;
Select Sname,sex,..... from students where sex=1;
Update table Set Fieldname= ' value ' where condition;
Insert into TableName (field1,field2,.......) VALUES (' value1 ', ' value2 ',......);
Insert into demo.students (sname,sex) VALUES (' xxx ', 0);
Delete from table where condition;

MySQL (Database)