Database applications account for 70% of computer applications, like computer programming, web design, data storage are used to it, it has a lot of products, such as: access, SQL server, MySQL, Oracle and so on. I think the learning of database can be viewed in this way, first, recognize the purpose, you learn the database is to do what? Is it computer programming, or web design, or you want to use it to store the company's material information. If the first two, you must learn SQL language, and then choose to operate a database product such as access, to skillfully operate it. But if the latter you need is a comprehensive knowledge of the database, SQL language is all the database products are common, or must learn, this time you can not learn some simple things, to learn more full-featured stronger, such as medium-sized databases SQL server, mega databases Oracle and so on. This depends entirely on your needs, but if you are designing a large e-commerce site to do efforts, that learning access is far from enough. Second, in order to comprehensively learn database knowledge, should be divided into two parts, first, now popular relational database basics must know, such as the ER model, attributes, records, the concept of linkage, the SQL language, etc., after learning but also to master the characteristics of each database, such as SQL server, Oracle's characteristics of which! --That's it, general part + special part. I hope my introduction is useful to you