Convert a ER model into a relational database schema expressed in SQL DDL, with appropriate constraints.

Use Create Table Command

Discussions and Comments

The following diagram shows entities, attributes and relationships for the discussions and comments in the pics.net site.

Comments on Discussions:

discussions are essentially holders for collections of comments

each discussion has an identifying numeric ID and may have a title (up to 50 chars)

a discussion contains one or more comments and is created when the first comment is posted

a collection of comments on one photo needs no title; the discussion is associated with the photo being commented on

discussions under a group will have a title and will be associated the group

Comments on Comments:

comments are messages posted by users as part of a discussion

each comment has an identifying numeric ID

the system time-stamps each comment with the precise posting date and time

the content of a comment is an arbitrary text string