MySQL Is the most popular relational database management system , stay WEB Application MySQL Is the best RDBMS(Relational Database Management System： Relational database management system ) One of the applications .
In this tutorial , Will let everyone quickly master MySQL Basic knowledge of , And easy to use MySQL database .
What is a database ？
database （Database） It is organized according to the data structure 、 A warehouse for storing and managing data .
Each database has one or more different API Used to create , visit , Administration , Search and copy saved data .
We can also store data in files , But the speed of reading and writing data in files is relatively slow .
So , Now we use a relational database management system （RDBMS） To store and manage large amounts of data . The so-called relational database , It is a database based on relational model , With the help of mathematical concepts and methods such as set algebra to process the data in the database .
RDBMS Relational database management system (Relational Database Management System) Characteristics of ：
- 1. The data appears in the form of a table
- 2. Each line has various record names
- 3. Each column is the data field corresponding to the record name
- 4. Many rows and columns form a form
- 5. A number of forms database
RDBMS The term
Before we start learning MySQL Before the database , Let's first understand RDBMS Some terms of ：
- database : A database is a collection of associated tables .
- data sheet : A table is a matrix of data . A table in a database looks like a simple spreadsheet .
- column : A column ( Data elements ) Contains the same type of data , For example, zip code data .
- that 's ok ： a line （= Tuples , Or record ） Is a set of related data , For example, a piece of data subscribed by a user .
- Redundancy ： Store twice as much data , Redundancy reduces performance , But it improves the security of data .
- Primary key ： The primary key is unique . A data table can only contain one primary key . You can use the primary key to query data .
- Foreign keys ： Foreign keys are used to associate two tables .
- Compound bond ： Compound bond （ Key combination ） Use multiple columns as an index key , Generally used for composite indexes .
- Indexes ： Use indexes to quickly access specific information in database tables . An index is a structure that sorts the values of one or more columns in a database table . A catalogue similar to a Book .
- Referential integrity : Referential integrity requires that nonexistent entities cannot be referenced in a relationship . And entity integrity are the integrity constraints that the relational model must meet , The purpose is to ensure the consistency of data .
MySQL It is a relational database (Relational Database Management System), This so-called " Relational " It can be understood as " form " The concept of , A relational database consists of one or more tables , A table as shown in the figure :
- Header (header): The name of each column ;
- column (col): A collection of data with the same data type ;
- that 's ok (row): Each line is used to describe the specific information of a record ;
- Worth (value): Line details , Each value must be of the same data type as the column ;
- key (key): The value of the key is unique in the current column .
MySQL Is a relational database management system , By Sweden MySQL AB The company developed , At present, it belongs to Oracle company .MySQL Is an associated database management system , Associated databases store data in different tables , Instead of putting all the data in one big warehouse , This increases speed and flexibility .
- MySQL It's open source , At present, it belongs to Oracle Its products .
- MySQL Support large databases . Can handle large databases with tens of millions of records .
- MySQL Use standard SQL Data language form .
- MySQL Can run on multiple systems , And support multiple languages . These programming languages include C、C++、Python、Java、Perl、PHP、Eiffel、Ruby and Tcl etc. .
- MySQL yes PHP There is good support ,PHP It is the most popular Web Development language .
- MySQL Support large databases , support 5000 A data warehouse of 10000 records ,32 Bit system table files can support up to 4GB,64 The largest table file supported by the bit system is 8TB.
- MySQL It can be customized , Adopted GPL agreement , You can modify the source code to develop your own MySQL system .
Before starting this tutorial, you should understand ？
Before starting this tutorial, you should understand PHP and HTML Basic knowledge of , And can be simply applied .
Many of the examples in this tutorial are related to PHP Language related , Our example basically adopts PHP Language to demonstrate .
If you don't know PHP, You can use the website's PHP course To understand the language .