我如何在数据库中实现标签？

I have an app and I want users to be able to add tags to articles (similar to stack overflows tags) but I want it to be dynamic. So far I have it as JSON strings (dont squirm too much) but this has a major shortcoming. Firstly I will show you an example, and then explain my problem.I have an app and I want users to be able to ad