I WOULD LIKE TO KNOW HOW TO REPRESENT ANY KIND OF CONSTRAINT IN AN ER DIAGRAM?
CAN WE REPRESENT EVERYTHING IN AN ER DIAGRAM i.e EVERY CONSTRAINT CAN IT BE REPRESENTED IN AN ER DIAGRAM?IF SO HOW?
ARE THERE ANY SET OF RULES WHICH WE CAN FOLLOW AND TELL WHETHER A CONSTRAINT CAN BE REPRESENTED IN AN ER DIAGARM?
I WOULD REALLY APPRECIATE IF SOMEONE GIVES ME PICTORIAL REPRESENTATIONS USING ER DIAGRAMS TO SHOW CONSTRAINTS.
Not all constraints can be shown in an ER diagram. You can usually show the primary unique identifier, and of course foreign keys (as relationships). You can also show cardinality rules on relationships. You can't show check constraints and multi-table constraints other than foreign keys (such as: "no two periods of assignment for an employee may overlap")
I can't help with the pictorial examples, as I personaly use Barker notation which seems to be peculiar to Oracle and is probably not what you would be using.