DDD全名叫做Domins drives Design；领域驱动设计。再说的通俗一点就是：通过领域建模的方式来实现软件设计。
.NET生成微信小程序推广二维码
爬虫（Web Scraping）是指通过编程自动化地获取互联网上的信息的过程。爬虫的目的通常是从网页中抓取数据，进行数据分析、处理或展示。
.NET中至少有6种定时器，每一种定时器都有它的用途和特点。根据定时器的应用场景，可以分为UI相关的定时器和UI无关的定时器。本文将简单介绍这6种定时器的基本用法和特点。
定义委托编译器会自动生成一个类派生自System.MulticastDelegate，这个类包含4个方法：一个构造器、Invoke、BeginInvoke、EndInvoke。
Lost connection to MySQL server…
[ERROR] InnoDB: Expected to open 3 undo tablespaces but was able to find only 0 undo tablespaces. Set the innodb_undo_tablespaces parameter to the correct value and retry. Suggested value is 0
ERROR 1418 (HY000): This function has none of DETERMINISTIC, NO SQL, or READS SQL DATA in its declaration and binary logging is enabled (you *might* want to use the less safe log_bin_trust_function_creators variable)
Error Code: 1175. You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column.
Error 1390 (HY000): Prepared statement contains too many placeholders
