database difference doing best practices

how hoop database exceptions your application?

are perplexing countenance information before flitting db only relying db schema validation logic?

do try redeem kind db errors (e.g. timeouts)?

here approaches:

1. validate information before flitting db


2. left validation db hoop db exceptions properly


3. validate both sides


4. validate apparent constraints business explanation left challenging validation db

what proceed use? why?

updates:

i'm blithe flourishing discussion.

let’s try sum adult village answers.

suggestions:

• validate both sides


• check business explanation constraints on
  client side, let db trust checks


• check early prevaricate bothering db


• check early provoke user trust


• keep db interacting formula place to
  simplify growth


• object-relational mapping (nhibernate, linq, etc.) assistance understanding constrains


• client side validation required confidence reasons

do have anything else say? converted validation specific question. blank core, i.e. "database associated blunder best practices" ones hoop ones gurgle up?