Mysql is the most popular relational database management system, and MySQL is one of the best RDBMS (Relational Database Management System: relational database management system) application software in WEB application.
First I want to ask what is a database?
A database is a warehouse that organizes, stores and manages data according to the data structure.
Each database has one or more different API (Application Programming Interface, application programming interface) is a number of predefined functions , the purpose is to provide applications and developers based on a certain software or hardware to access a set of routines , without having to access the source code, or understand the details of the inner workings . For creating, accessing, managing, searching and duplicating stored data.
We can also store data in files, but reading and writing data in files is relatively slow.
So, now we use relational database management systems (RDBMS) to store and manage large volumes of data. The so-called relational database is a database based on the relational model, which uses mathematical concepts and methods such as set algebra to process the data in the database.
Features of RDBMS (Relational Database Management System):
- 1. The data is presented in the form of a table
- 2. Each row 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. Several forms form a database
RDBMS terminology
Before learning MySQL database, let's first understand some terms of RDBMS:
- Database: A database is a collection of related tables.
- Data table: A table is a matrix of data. A table in a database looks like a simple spreadsheet.
- Column: A column (data element) that contains the same data, such as zip code data.
- Row: A row (=tuple, or record) is a group of related data, such as a piece of data subscribed by a user.
- Redundancy : Stores twice the data. Redundancy reduces performance but improves data security.
- 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 Key: A foreign key is used to relate two tables.
- Compound key : A compound key (composite key) uses multiple columns as an index key and is generally used for compound 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 no reference to a non-existent entity be allowed in a relationship. Entity integrity is an integrity constraint that a relational model must satisfy, in order to ensure data consistency.
Mysql database
MySQL is a relational database management system developed by the Swedish MySQL AB company and currently belongs to the Oracle company. MySQL is a relational database management system, relational databases keep data in different tables instead of keeping all the data in one big warehouse, which increases speed and improves flexibility.
- Mysql is open source, so you don't need to pay extra.
- Mysql supports large databases. Can handle large databases with tens of millions of records.
- MySQL uses the standard SQL data language form.
- Mysql can be allowed on multiple systems and supports multiple languages. These programming languages include C, C++, Python, Java, Perl, PHP, Eiffel, Ruby, and Tcl, among others.
- Mysql has good support for PHP, which is currently the most popular web development language.
- MySQL支持大型数据库，支持5000万条记录的数据仓库，32位系统表文件最大可支持4GB，64位系统支持最大的表文件为8TB。
- Mysql是可以定制的，采用了GPL协议，你可以修改源码来开发自己的Mysql系统。