有的我们希望在指定时间运行数据库的相关操作，如果这些在WEB前台来执行将会非常浪费服务器资源，因为网页需要不停的刷新继而判断
有的我们希望在指定时间运行数据库的相关操作，如果这些在WEB前台来执行将会非常浪费服务器资源，，因为网页需要不停的刷新继而判断时间来执行操作。。。
我是用的这样的方法
1. 在/etc 创建一个目录 crond.my
2.编辑/etc/crontab
分 小时 天 月 星期 root run-parts /etc/cron.my
3. 在cron.my中创建delete_table_msg.sh
内容如下：
/usr/local/MySQL/bin/MySQL -hlocalhost -uroot -pwowangle
上边为什么要下MySQL的绝对路径？因为我的MySQL是自己编译的，而这个MySQL命令并没有在crontab的PATH中存在.
请看一下/etc/crontab文件的PATH就完全明白了！
有的时候时候定时脚本没有运行就请选查看你的命令是否在path当中！
那个job.sql当中就是要执行的sql语句
！（题外话了）
你要对SQL有更多的了解！才会能完成更多的任务！所以SQL很重要！对WEB开发人员更是如此，我不相信一个用DW的可以成为什么优秀的WEB程序人员，如是你只是会简单的select * from table 这样类似的语句那你和我一样也该好好反醒一下了！
我的这个A.SQL中是如下内容<br>use xfcz;<br>delete from t;<br>
看就这么两条简单的语句，因为这个T表中的数据在每天固定的一个时间是必须全部清除的
发挥你的想象力，重头戏就在这个sql当中......
MySQL's Place: Databases and ProgrammingApr 13, 2025 am 12:18 AMMySQL'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
MySQL: From Small Businesses to Large EnterprisesApr 13, 2025 am 12:17 AMMySQL is suitable for small and large enterprises. 1) Small businesses can use MySQL for basic data management, such as storing customer information. 2) Large enterprises can use MySQL to process massive data and complex business logic to optimize query performance and transaction processing.
What are phantom reads and how does InnoDB prevent them (Next-Key Locking)?Apr 13, 2025 am 12:16 AMInnoDB effectively prevents phantom reading through Next-KeyLocking mechanism. 1) Next-KeyLocking combines row lock and gap lock to lock records and their gaps to prevent new records from being inserted. 2) In practical applications, by optimizing query and adjusting isolation levels, lock competition can be reduced and concurrency performance can be improved.
MySQL: Not a Programming Language, But...Apr 13, 2025 am 12:03 AMMySQL is not a programming language, but its query language SQL has the characteristics of a programming language: 1. SQL supports conditional judgment, loops and variable operations; 2. Through stored procedures, triggers and functions, users can perform complex logical operations in the database.
MySQL: An Introduction to the World's Most Popular DatabaseApr 12, 2025 am 12:18 AMMySQL 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.
The Importance of MySQL: Data Storage and ManagementApr 12, 2025 am 12:18 AMMySQL is an open source relational database management system suitable for data storage, management, query and security. 1. It supports a variety of operating systems and is widely used in Web applications and other fields. 2. Through the client-server architecture and different storage engines, MySQL processes data efficiently. 3. Basic usage includes creating databases and tables, inserting, querying and updating data. 4. Advanced usage involves complex queries and stored procedures. 5. Common errors can be debugged through the EXPLAIN statement. 6. Performance optimization includes the rational use of indexes and optimized query statements.
Why Use MySQL? Benefits and AdvantagesApr 12, 2025 am 12:17 AMMySQL 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.
Describe InnoDB locking mechanisms (shared locks, exclusive locks, intention locks, record locks, gap locks, next-key locks).Apr 12, 2025 am 12:16 AMInnoDB's lock mechanisms include shared locks, exclusive locks, intention locks, record locks, gap locks and next key locks. 1. Shared lock allows transactions to read data without preventing other transactions from reading. 2. Exclusive lock prevents other transactions from reading and modifying data. 3. Intention lock optimizes lock efficiency. 4. Record lock lock index record. 5. Gap lock locks index recording gap. 6. The next key lock is a combination of record lock and gap lock to ensure data consistency.
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
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
MantisBT
Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
