网络聊天应用数据库方案

Question

I am making a classified like web application where I want to implement a chat message module. While searching on Internet I found a database scheme ERD Diagram.

I am able to understood it but one thing is confusing me is is_from_sender column in message entity . I found the sample data which is this . Since I am a beginner I need a little explanation how this works , why using is_from_sender?

Answer 1

I think that the purpose of the is_from_sender column, which is a boolean field, is to differentiate each message whether it comes from the sender or from the receiver in order to make some logic on it in the application. For example: my messages will be shown in grey background and the receiver will be in blue background. This ERD is modeled in a way that you cannot know who sent it (only who initiated the conversation by the header). The designer wanted to know this information so instead of adding to message table an int column of the sender user id (foreign key), he just added a bit column which is less expansive is size