The goal of this work is to understand the difference between vertical structure and horizontal structure on data management. We take adverse event report as an example to find out the relationship between the storage space and the factors related to the trail. From the study we find out the difference of storage space between horizontal structure and vertical structure goes up with the increase of the storage space of each adverse event record and the number of adverse event allowed to record in the horizontal structure and goes down with the increase of the happening rate and the average times of the adverse event. When using the most widely used study design, vertical structure always takes less storage space than the horizontal structure. This vertical structure database is more suitable for the data management than the horizontal structure database.