SQL是使用最为广泛的数据库语言。不管你是应用开发者、数据库管理
员、Web应用设计师、移动应用开发人员，还是只使用Microsoft Office，
掌握良好的SQL知识对用好数据库都是很重要的。(QL is the most widely used database language. Whether you're an application developer or database manager
Are you a Web application designer, a mobile application developer, or just using Microsoft Office?,
A good knowledge of SQL is very important for using a database well. Change. Used in industrial control industry)