This is the 10th day of my participation in the August More Text Challenge. For details, see:August is more challenging

First, the introduction of database

A database is a warehouse used to store data.

1.1 SQL

Structured Query Languages are a language used to operate relational databases. They are the general operating language of relational databases. Common relational databases:

1.2 Connecting to the mysql server on Windows

1. You can use Navicat or mysql-front. Here I’m using Navicat, as shown below:

Connect to mysql using Navicat:

This should be empty by default, this is the database that I tested earlier. Click Connection and select MySQL. The following interface appears:

My initial password is 123456. OK, and you’re ready to connect. As shown in figure:This is the same table that I used to look at some open source projects.

2. You can also connect with phpMyadmin, which has been configured before, so let’s open it directly, as follows:

Click execute, as follows:

3. Connect through wAMP

As shown in the figure, open MySQL Console.

Appear as shown in figure

Enter your password and press Enter to enter the connection:Mysql > select * from ‘bin’ where ‘bin’ = ‘bin’; mysql > select * from ‘bin’ where ‘bin’ = ‘bin’;

The command	Command meaning
-h	host
-p	port
-u	user
-p	password
Enter the following names:
The connection is successful and you can write some mysql statements to query.
If you connect to a local database,-hYou can omit it. If the port number is 3306, the port number-PYou can also omit, useexitorquitor\qCommand to exit:
Next type the omitted command:
That’s okay, too.

• Ciphertext connection via command line:

Two, the basic concept and operation of the database

2.1 Basic Concepts of the Database

• Database: A database stores tables. A database can store multiple tables
• Table: used to store data
• Relationship: A common field for two tables
• Line: also known as record, also known as entity
• Column: also called field, also called attribute

In terms of table structure, tables are divided into rows and columns; In terms of table data, the table is divided into records and fields; In object-oriented terms, a record is an entity and a field is an attribute.

Database execution process:

2.2 Database Operations

Open the terminal command line and connect to the database:

2.2.1 Viewing the Database

To view all databases: show databases;

2.2.2 Creating a Database

Create database:Create Database Database name:

An error occurs when creating an existing database:When creating a database, determine whether the database exists, create it only if it does not exist, syntax:Create database if Not EXISTS Database name; Special characters, keywords for database name:You can see the error. If you want to use special characters or keywords for the database name, you can use ·· Enclose the database name:

When creating the database, specify the encoding. If not specified, the installation encoding will be usedshow variables like 'character_set_%';:You can specify the database code when creating a data database. Syntax:create database emp charset=utf8;The database is stored in the data folder:You can also change the save address of the database in the my.ini configuration file:Set the character set and proofread set for the database in the db.opt file:

2.2.3 Deleting a Database

Grammar:Drop Database if exists Data name;

2.2.4 Displaying database creation information

Grammar:show create database emp;

2.2.3 Modifying the Database

When you change a database, you can only change the database options, and the database options only have character encoding. grammarAlter database database name charset= character encoding;

2.2.4 Using the Database

Syntax: use database name;

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