


Detailed explanation of sample code for mysql delete multi-table connection deletion function
This article mainly introduces mysql delete Related information about the multi-table connection deletion function. Friends in need can refer to
for a single table Delete:
DELETE FROM tableName WHERE columnName = value; 删除表内的所有行: 即:保留表的结构、属性、索引 DELETE FROM tablename; DELETE * FROM tablename;
Delete all content in the same table (delete data, table structure)
TRUNCATE customer;
Cannot report how many rows were deleted, and can only be used for a single table
Multi-table connection deletion:
DELETE orders,itrms FROM orders,items WHERE orders.userid = items.userid AND orders.orderid = items.orderid AND orders.date<"2000/03/01";
The name of the table to be deleted is listed after DELETE, and the table used in the connection condition is listed after FROM
Assumed deletion All wineries in the BV region, but do not delete the place name
DELETE winery FROM region,winery WHERE winery.regionid = region.regionid AND region.regionname = 'BV';
The query only affects the winery table, but also uses winery and region to find the records that need to be deleted
Use advanced connection query
DELETE orders,items FROM orders INNER JOIN otems ON orders.orderid = items.orderid AND orders.userid = items.userid WHERE orders.date<"2000/03/01";
You can also use nested queries in the DELETE statement (internal queries cannot reference deleted data), GROUP BY, HAVING;
You can also use ORDER BY in a single table query, singular unless used in conjunction with LIMIT Delete some data rows, otherwise it doesn't make much sense.
Add quick modifier to quickly delete index entries and accelerate large or frequent deletion operations
DELETE QUICK FROM customer WHERE userid<10;
Can only be used for tables of type MyISAM
Clean MyISAM tables
OPTIMIZE TABLE customer;
The above is the detailed content of Detailed explanation of sample code for mysql delete multi-table connection deletion function. For more information, please follow other related articles on the PHP Chinese website!

Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

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

Hot Article

Hot Tools

Notepad++7.3.1
Easy-to-use and free code editor

SublimeText3 Chinese version
Chinese version, very easy to use

Zend Studio 13.0.1
Powerful PHP integrated development environment

Dreamweaver CS6
Visual web development tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

Hot Topics

MySQL is an open source relational database management system, mainly used to store and retrieve data quickly and reliably. Its working principle includes client requests, query resolution, execution of queries and return results. Examples of usage include creating tables, inserting and querying data, and advanced features such as JOIN operations. Common errors involve SQL syntax, data types, and permissions, and optimization suggestions include the use of indexes, optimized queries, and partitioning of tables.

MySQL's position in databases and programming is very important. It is an open source relational database management system that is widely used in various application scenarios. 1) MySQL provides efficient data storage, organization and retrieval functions, supporting Web, mobile and enterprise-level systems. 2) It uses a client-server architecture, supports multiple storage engines and index optimization. 3) Basic usages include creating tables and inserting data, and advanced usages involve multi-table JOINs and complex queries. 4) Frequently asked questions such as SQL syntax errors and performance issues can be debugged through the EXPLAIN command and slow query log. 5) Performance optimization methods include rational use of indexes, optimized query and use of caches. Best practices include using transactions and PreparedStatemen

Apache connects to a database requires the following steps: Install the database driver. Configure the web.xml file to create a connection pool. Create a JDBC data source and specify the connection settings. Use the JDBC API to access the database from Java code, including getting connections, creating statements, binding parameters, executing queries or updates, and processing results.

MySQL is chosen for its performance, reliability, ease of use, and community support. 1.MySQL provides efficient data storage and retrieval functions, supporting multiple data types and advanced query operations. 2. Adopt client-server architecture and multiple storage engines to support transaction and query optimization. 3. Easy to use, supports a variety of operating systems and programming languages. 4. Have strong community support and provide rich resources and solutions.

The process of starting MySQL in Docker consists of the following steps: Pull the MySQL image to create and start the container, set the root user password, and map the port verification connection Create the database and the user grants all permissions to the database

The main role of MySQL in web applications is to store and manage data. 1.MySQL efficiently processes user information, product catalogs, transaction records and other data. 2. Through SQL query, developers can extract information from the database to generate dynamic content. 3.MySQL works based on the client-server model to ensure acceptable query speed.

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.

The key to installing MySQL elegantly is to add the official MySQL repository. The specific steps are as follows: Download the MySQL official GPG key to prevent phishing attacks. Add MySQL repository file: rpm -Uvh https://dev.mysql.com/get/mysql80-community-release-el7-3.noarch.rpm Update yum repository cache: yum update installation MySQL: yum install mysql-server startup MySQL service: systemctl start mysqld set up booting
