Home Backend Development PHP Tutorial MySQL's first introduction to sql statements and library operations

MySQL's first introduction to sql statements and library operations

May 09, 2018 am 09:38 AM
mysql sql statement operate

MySQL’s initial understanding of sql statements and library operations is very important for PHP operations. This article will explain the related operations in detail.

1>Types of SQL language

SQL: Structured Query Language Structured Query Language

## SQL language is mainly used for access Data, query data, update data and manage relational database systems, SQL language developed by IBM


-->DDL statement Database definition language: database, table, view, index,

storage Process , such as CREATE DROP ALTER -->DML statement Database manipulation language:
Insert dataINSERT, delete data DELETE, update data UPDATE, query data SELECT

-->

DCL statement Database control language: For example, controlling user access rights GRANT, REVOKE

It is essentially to control folders (databases), files (tables), and Add, delete, modify and check file content (data records)


1.1>Operate folder (database)


As follows,

Create databasedb1, Essentially, a new db1 folder is created under the data directory, and

data management files are created by default under the db1 folder.


       


##                                                                                                                                                            Check: show databases; # View all libraries

## Show create database db1; # View a single library


Change: alter database db1 charset latin1;


Delete: drop database db1;

1.2>Operating files (tables)


Which database to operate under, use use library name to switch to the library, you can use select database (); View the current database.


As above, table t1 is created, and two files are generated correspondingly. .frm is the file that stores the table structure, and .ibd is the file that stores the corresponding table. data file.

                                                                                                                                                                              Since


: Show Tables;#Look at all tables

Show Create Table T1;#View a single table

# Desc T1;

                                                                                                                                                                                    modify name char(3); t1;


1.3>Operate file content (data records in the table)

Add: insert into t1 values(1,'egon1'),(2, 'egon2'),(3,'egon3'); # Insert multiple pieces of data

Query: select * from t1; Specify the column

                                                                                            use out out out out out out out through out using           out out through ’ ’ s ’ through ’ use ’ s ’ through ’ through ’ through ‐ to ‐‐‐‐‐‐ lead to t1 to t1 where id=1;
2>Library related

2.1>The uses of some libraries under database.

Information_schema: Virtual library, which does not occupy disk space and is stored in memory. It is generated when the database service is started.

This library stores are some parameters after the database is started, such as user table information, column information, permission information, character information, etc.

So as shown below, the library can be viewed on the command line, but the file cannot be seen on the hard disk.

Performance_schema: A new database has been added since MySQL 5.5: mainly used to collect database server performance parameters,
Record various events, locks, etc. that occur when processing query requests Phenomenon

mysql: Authorization library, mainly stores the permission information of system users


This article is the first introduction to MySQL SQL statements and library operations are explained. For more learning materials, please pay attention to the PHP Chinese website.

Related recommendations:

How to simply implement TP5-add, delete, modify and query

How to query the last record through mysql

sql server finds the maximum value, minimum value, maximum value corresponding time, and minimum value corresponding time

The above is the detailed content of MySQL's first introduction to sql statements and library operations. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial
1664
14
PHP Tutorial
1268
29
C# Tutorial
1246
24
Laravel Introduction Example Laravel Introduction Example Apr 18, 2025 pm 12:45 PM

Laravel is a PHP framework for easy building of web applications. It provides a range of powerful features including: Installation: Install the Laravel CLI globally with Composer and create applications in the project directory. Routing: Define the relationship between the URL and the handler in routes/web.php. View: Create a view in resources/views to render the application's interface. Database Integration: Provides out-of-the-box integration with databases such as MySQL and uses migration to create and modify tables. Model and Controller: The model represents the database entity and the controller processes HTTP requests.

MySQL and phpMyAdmin: Core Features and Functions MySQL and phpMyAdmin: Core Features and Functions Apr 22, 2025 am 12:12 AM

MySQL and phpMyAdmin are powerful database management tools. 1) MySQL is used to create databases and tables, and to execute DML and SQL queries. 2) phpMyAdmin provides an intuitive interface for database management, table structure management, data operations and user permission management.

MySQL vs. Other Programming Languages: A Comparison MySQL vs. Other Programming Languages: A Comparison Apr 19, 2025 am 12:22 AM

Compared with other programming languages, MySQL is mainly used to store and manage data, while other languages ​​such as Python, Java, and C are used for logical processing and application development. MySQL is known for its high performance, scalability and cross-platform support, suitable for data management needs, while other languages ​​have advantages in their respective fields such as data analytics, enterprise applications, and system programming.

Solve database connection problem: a practical case of using minii/db library Solve database connection problem: a practical case of using minii/db library Apr 18, 2025 am 07:09 AM

I encountered a tricky problem when developing a small application: the need to quickly integrate a lightweight database operation library. After trying multiple libraries, I found that they either have too much functionality or are not very compatible. Eventually, I found minii/db, a simplified version based on Yii2 that solved my problem perfectly.

Laravel framework installation method Laravel framework installation method Apr 18, 2025 pm 12:54 PM

Article summary: This article provides detailed step-by-step instructions to guide readers on how to easily install the Laravel framework. Laravel is a powerful PHP framework that speeds up the development process of web applications. This tutorial covers the installation process from system requirements to configuring databases and setting up routing. By following these steps, readers can quickly and efficiently lay a solid foundation for their Laravel project.

Solve MySQL mode problem: The experience of using the TheliaMySQLModesChecker module Solve MySQL mode problem: The experience of using the TheliaMySQLModesChecker module Apr 18, 2025 am 08:42 AM

When developing an e-commerce website using Thelia, I encountered a tricky problem: MySQL mode is not set properly, causing some features to not function properly. After some exploration, I found a module called TheliaMySQLModesChecker, which is able to automatically fix the MySQL pattern required by Thelia, completely solving my troubles.

MySQL: Structured Data and Relational Databases MySQL: Structured Data and Relational Databases Apr 18, 2025 am 12:22 AM

MySQL efficiently manages structured data through table structure and SQL query, and implements inter-table relationships through foreign keys. 1. Define the data format and type when creating a table. 2. Use foreign keys to establish relationships between tables. 3. Improve performance through indexing and query optimization. 4. Regularly backup and monitor databases to ensure data security and performance optimization.

MySQL: Key Features and Capabilities Explained MySQL: Key Features and Capabilities Explained Apr 18, 2025 am 12:17 AM

MySQL is an open source relational database management system that is widely used in Web development. Its key features include: 1. Supports multiple storage engines, such as InnoDB and MyISAM, suitable for different scenarios; 2. Provides master-slave replication functions to facilitate load balancing and data backup; 3. Improve query efficiency through query optimization and index use.

See all articles