Making sure users enter quality information into the database is an important aspect of developing a collaborative tool that can be used as a valuable teaching resource. Be sure to educate your learners about entering quality data instead of just populating it willy-nilly. Structure is only one aspect of a database. Learners often enter information based on their knowledge and understanding of the purpose of the database and its goals. Don't be shy about going over organization, accuracy, and interpretation — grasping those elements can become a learning exercise. However much you introduce the concept, as the database grows, you need to track the information to ensure the information's consistency and accuracy.
Moodle has added a number of tools that help you manage the information and ensure the quality of the entries. (You can either set these options when you first create your database or go back later and enable them.)