Domain integrity check in application

Is it better to check for allowed domain values on the frond end or let the database engine handle the domain integrity. For example If you have a data entry form for employee, is it better to check for allowed values on the data entry form before submitting the data to the database assuming network IO is not a big issue. What if there are lots of checks to be performed, would the engine be faster or would checking the value on the front end take the load of the dB engine?

Appropriate use of SQL CLR

We have some back end processes that runs* on our sql server (SQL Server), they involve processing claims. This requires both data manipulation (biz logic) and data read/write to tables. The biz logic contained should never be used by any of our end user (web/fat client) applications, just for this (runs once, nightly) process.

Accessing Repositories from Domain

Say we have a task logging system, when a task is logged, the user specifies a category and the task defaults to a status of ‘Outstanding’. Assume in this instance that Category and Status have to be implemented as entities. Normally I would do this:

Aggregate root & Repository dilemma

I am in a big dilemma here.

How do you handle objects that need custom behavior, and need to exist as an entity in the database?

For a simple example, assume your application sends out notifications to users when various events happen. So in the database I might have the following tables:

When should we use weak entities when modelling a database?

This is basically a question about what are weak entities? When should we use them? How should they be modeled?

ORM: Keep entities coherent in a cache or retrieve entities each time?

We have a tricky question in a project using Java & Hibernate, with a model containing bi-directional relationships.

OO Design: hint EntityManager to preload some datasets

say I have an EntityManager that can read(PK) a dataset from the DB and return it.

How do I manage multiple relationships from a software design perspective?

How do I go about managing projects when there are two fundamental relationships that need to be maintained? The most obvious example that I can think of would be a firm doing some kind of location-based consulting.

Unique Value Object vs Entity

Trying to convert some entities into value objects I am stuck in a case where what seems a value object must be unique within an aggregate.