Q:

Software design approach for large relational database

I am working on a personal side project that will utilize a complex and large relational database. During the design of the database I had some co-workers give advice to how I should approach my application; they advised to use the entity framework.
From what I've read and what I am watching it sounds like the entity framework is the right tool for the job. However what I have come to programmer.stackexchange for is to ask whether or not somebody who has just going going in their career should do. 
Let me rephrase; I have 3 years web design / development experience (html/css/js/php/mysql) and now about 1 year experience with actual software engineering C#/VB. So the question is should I utilize the entity framework or should I build this rather complex and ambitious project without the entity framework; ergo building all the SQL that will handle massive amounts of relational data?
The reason why I ask is because I want to get the most ROI (knowledge and experience) from the project.

A:

will utilize a complex and large relational database

OR mappers like EF can help you to avoid tedious work with "complex" models. You have to write less code, especially less CRUD code. On the other hand, when handling a "large" database (in terms of massive amounts of relational data, as you wrote), you have to be careful that the OR mapper does not produce more problems than it solves for you. For such kind of DB, you will typically have to make use of fine-tuned SQLs, SQL bulk processing, stored procedures etc., all things where ORM won't be helpful.
And even when large just means "lot of tables and relations", EF may become a bottleneck, see the links behind this forum post:
http://social.msdn.microsoft.com/Forums/en/adodotnetentityframework/thread/a0f6c057-558c-45d1-98e6-231cc0a41613
Those SO links may be helpful for you, too:
https://stackoverflow.com/questions/6185918/entity-framework-4-1-for-large-number-of-tables-715
https://stackoverflow.com/questions/2981054/entity-framework-4-handling-very-large-1000-tables-data-models

A:

Both approaches will lead to you learning useful, but different skills.
One will help you learn the intricacies of EF, the other will allow you to better learn the raw tsql. 
I would consider both important. So, shouldn't you pick what is best for this particular case (EF) and learn it?
There is endless knowledge that can be acquired, concentrate your efforts on the most immediately beneficial.

