MySQL First knowledge

A: Database overview

1. What Is Data

The symbolic records describing things are called data, and the symbols describing things can be either numbers or text, pictures, images, sounds, languages, etc., and the data is represented by many forms, which can be digitized and stored in a computer,

2. What is a database (db)

The database is the warehouse where the data is stored, except that the warehouse is on a computer storage device, and the data is stored in a certain format.

In the past, people stored data in cabinets, and now the volume of data is large, no longer applicable

Database is a long-term storage in the computer, organized, shareable data can be.

The data in the database is organized, described and stored according to a certain data model, with small redundancy, high data independence and extensibility, and can be shared for various users.

3. Database management System (DBMS)

After understanding the concept of data and DB, how to organize and store it scientifically, how to efficiently acquire and maintain data becomes the key

This is the use of a system software---database management system

such as MySQL, Oracle, SQLite, Access, MS SQL Server

MySQL is mainly used for large-scale portals, such as Sogou, Sina, etc., its main advantage is open source code, because the open source of this database is free, he is now the Oracle company's products.
Oracle is mainly used in banks, railways, airports, etc. The database is powerful and the software is expensive. It is also the product of Oracle Corporation.
SQL Server is Microsoft's products, mainly used in large and medium-sized enterprises, such as Lenovo, founder and so on.

4 The relationship between database server, data management system, database, table and record (Key Understanding!!!) ）

Entries: 1 Liu Hailong 324245234 22 (information in multiple fields consists of one record, that is, a line of content in the file)

Table: student,scholl,class_list (i.e. file)

Database: Oldboy_stu (that is, folder)

Database management system: such as MySQL (is a software)

Database server: One computer (high memory requirements)

Summarize:

Database server-: Running database management software

Database management software: Management-Database

Database: A folder for organizing files/tables

Table: A file that is used to hold multiple lines of content/Multiple records

II: MySQL Introduction

MySQL is a relational database management system developed by the Swedish MySQL AB company, currently owned by the Oracle company. MySQL's most popular relational database management system, MySQL is one of the best RDBMS (relational database Management system, relational databases management systems) application software in WEB applications.

With MySQL, this database software can free the programmer from the management of the data, and focus on the programming logic.

MySQL Server software is mysqld to help us manage folders and files, provided that we as users, we need to download MySQL client, or other modules to connect to mysqld, and then use the syntax format specified by the MySQL software to submit their own commands, Implements the management of folders or files. The syntax is SQL (structured query Language, which is the structured Queries language)

The SQL language is primarily used to access data, query data, update data, and manage relational database systems, which are developed by IBM. There are 3 types of SQL languages: #1, DDL Statement    database Definition language: Databases, tables, views, indexes, stored procedures, such as Create DROP alter#2, DML statement    database manipulation languages: Insert data inserts, delete data deletes, Updated data update, query data select#3, DCL statement    Database Control Language: for example, to control user access rights grant, REVOKE

MySQL First knowledge