In this chapter, we had an introduction to information systems such as OLTP and OLAP. Then, we discussed the difference between snowflake, star schema, and relational database design models. After that, we talked about design traps and how they will affect our SQL query. Then, we went through many design traps such as fan, chasm, and loops. Later on, we got to know how to fix each trap using advanced Data Foundation features such as contexts, aliases, and shortcut joins. In the next chapter, we will talk about advanced Business layer features that we haven't introduced yet.