Basic MySQL database tutorial

Databases have evolved from a simple collection of data files to today's large database governance systems, which have become an indispensable part of our daily lives. Without the help of databases, many simple tasks will become tedious and even difficult to implement. In particular, large organizations such as banks, schools, and libraries rely more on database systems for their normal operation. Looking at the Internet, from search engines to online malls, from online chat to email lists, all of them are inseparable from databases.

Currently, database products on the market are diverse. From solutions for large enterprises to small application systems for small and medium-sized enterprises or individual users, these products can meet the diversified needs of users. Here, we will introduce you to the MySQL database, which is one of the many relational database products. Compared with other systems, MySQL database can be called the fastest running SQL language database. In addition to the features and options that many other databases do not have, MySQL database is a completely free product. Users can directly download databases from the internet for personal or commercial purposes, instead of paying any fees (download site http://www.mysql.com is recommended ).

In general, MySQL databases have the following main features:

1. The number of users accessing the database at the same time is not limited;

2. More than 50,000,000 records can be saved;

3. It is the fastest-running database system in existing products on the market;

4. The user permission settings are simple and valid.

Today, well-known international companies, including Siemens and Silicon Graphics, have begun to use MySQL as their database governance systems, which further confirms the superior performance of MySQL databases and broad market development prospects.

This article will focus on some basic operations of the MySQL database, including how to establish a connection with the database, how to set the database, and how to execute basic commands. It is expected to help readers learn and grasp the MySQL database.


Getting started

In general, when accessing the MySQL database, we first need to use telnet to remotely log on to the server where the database system is installed, and then enter the MySQL database. The MySQL database connection command is as follows:

Mysql-h hostname-u username-p [password]

Or:

Mysql-h hostname-u username -- password = password

Here, hostname is the name of the server with the MySQL database installed, and username and password are the user's login name and password respectively.

If the MySQL database is correctly installed and configured, you will receive the following system feedback after entering the preceding command:

Welcome to the MySQL monitor. Commands end with; or g.

Your MySQL connection id is 49 to server version: 3.2 3-beta-log

Type help for help.

Mysql>

In this way, the user successfully enters the MySQL database system and can enter various commands at the mysql> command prompt. Below, we will list some major MySQL database governance commands for your reference. You can also enter help, h, or? Get a brief description of the following commands.

Mysql> help

Help (h) display command help

? (H) Same as above

Clear (c) clear screen content

Connect (r) to reconnect to the server. The optional parameters are db (database) and host (server)

Exit () to exit the mysql database, which serves the same purpose as the quit command

Go (g) sends commands to the mysql database

Print (p) print the current command

Quit (q) exits mysql database

Status (s) displays the current server information

Use (u) to open the database and use the database name as the command parameter

The preceding commands are mainly used for system management of MySQL databases. If you need to operate a specific database, you can use the use command to enter the database. The format is as follows:

Mysql> use dbname;

Here, you need to note that the MySQL database requires the user to use ";" at the end of all commands as the command Terminator.


Data types and data tables

In essence, a database is a growing and complex data organization structure. In MySQL databases, the structure used to save data records is called a data table. Each data record is composed of smaller data objects, namely, data types. Therefore, one or more data types constitute one data record, one or more data records form one data table, and one or more data tables form one database. We can understand the above structure as follows:

Database <Table <Record <Datatype

Data types are divided into different formats and sizes, allowing database designers to create the most ideal data structure. Correct selection of appropriate data types has an important impact on the performance of the final Database. Therefore, we need to first introduce the concepts of data types in detail.