When you are creating a system and have a database that you will be using, then you need to create an entity-relationship diagram (ERD) and a data dictionary. While creating new requirement for a new interface, I asked if they needed any assistance creating an ERD. They looked at me like I was crazy. Like I always say, documentation is always the first piece to get ignored when teams are trying to quickly design and deploy a system. As is always the case, they quickly realized during user-acceptance testing, that they did not fully understand the table fields, its values, and relationships. Another reason is you have to think ahead. What would happen if you database person or developer leaves? How will you get his/her replacement up to speed?
An ERD is a pictorial view of the database that shows the relationships between the entities. You usually have one table and it’s entities listed. You form a line between the entity that is connected (or related) to another entity in another table. You show if it has a 1-to-1 relationship, 1-to-many relationship, or many-to-many relationship. You also want to list next to the entity what kind of value it has. For instance, it can be an integer, date/time, string, etc. If you are developing a new system, then there is definitely a lot of analysis that needs to be done. However, you have to do it. It will save you some headaches in the future.
A data dictionary goes hand-in-hand with an ERD. It lists all the entities, entity type, location, and any other important information that will be needed to design and develop the system. Data dictionaries are usually in a tabular format, so you don’t have to spend countless hours writing, but you do have to spend it with Subject-Matter Experts thinking about it. Please make sure that your data dictionary and ERD do not have conflicting information. If it does, then your team is not on the same page, and this can be disastrous.
If you are the Technical Writer, then you should be in there helping to create these documentation. Learning the system’s database, will give you tons of knowledge that will make later documents a breeze.