Preparation Is Key To Succesful Job Interviews
To jump start your IT career, it is not enough that you have with you during job interviews the best well-prepared resume. Of foremost importance is mental toughness and psychological readiness, meaning you are ready for any job interview questions that may be thrown at you without showing any vestige of doubt and uncertainty about [...]
Referential Integrity in Relational Database
In this blog post, let’s at the decomposition of relations to minimize redundancy and at foreign keys to implement the links between relations. If these links are ever broken, the system will be unreliable at best and unusable at worst. Referential integrity constraints maintain and protect these links. There is really only one referential integrity [...]
Transition Integrity in Relational Database
You would use transitional integrity constraints, for instance, to ensure that the status of a given order never changed from “Entered” to “Completed” without passing through the interim states, or to prevent a canceled order from changing status at all. The status of an entity is usually controlled by a single attribute. In this case, [...]
Domain Integrity in Relational Database
A domain is the set of all possible values for a given attribute. A domain integrity constraint—usually just called a domain constraint—is a rule that defines these legal values. It might, of course, be necessary to define more than one domain constraint to describe a domain completely. A domain isn’t the same thing as a [...]
Functional Dependency in Relational Database
Functional Dependency in Relational Database The concept of functional dependency is an extremely useful tool for thinking about data structures. Given any tuple T, with two sets of attributes {X1…Xn} and {Y1…Yn} (the sets need not be mutually exclusive), then set Y is functionally dependent on set X if, for any legal value of X, [...]