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HIM 650 Topic 3 DQ 1
answer
The logical design of your database, or ER diagram, is a critical step in the creation of a database. By creating a logical design for your database you will not only have a better understanding of what data you need but it will also be easier to build and maintain the database later on. One of the main benefits of using an ER diagram is that it helps to create a structure for similar types of data. This can save time and money in the long run as it makes it easier to determine what needs updating when new data has been collected.
Using an Entity Relationship diagram to aid the design process is a useful way to understand the conceptual model of your application. Your conceptual model defines how all the relevant information flows through the system, and helps you and future developers capture the intent of how data is processed. Placing data into tables without connecting those tables and ensuring that you have multiple ways to view information can make it difficult to understand interactions between pieces of data. This can lead to inconsistent data and unexpected data loss. By having a physical model in sync with your conceptual model, you avoid these risks. As a side effect, you also get facilities for free, such as transactional integrity.
This approach is not intuitive, so it can be difficult to understand. It is however, one of the best approaches to use when you have a large number of entities and relationships that need to be well understood. This can also help with identifying redundancies between different entities and relationships that would otherwise be missed.
 
 
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question
What are the benefits or disadvantages of ER diagrams? Why bother with logical design and not just create tables and columns (physical design) directly?