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Define Assertions in SQL
a. An assertion is a predicate that is expressing a condition we wish the database to always satisfy.
b. Domain constraints, functional dependency and referential integrity are unique forms of assertion.
c. In which a constraint cannot be expressed in these forms, we use an assertion, for example
Update Anomaly : This anomaly is occurred due to data redundancy. Redundant information makes updates more complex since, for example, varying the name of the instructor of MCS-014
What is a super key? A super key is a set of one or more attributes that collectively permits us to recognize uniquely an entity in the entity set.
Write a Query that uses the UNION Operator 1. Use the Software Experts database to: a. Display the first and the last name of all consultants who worked on any projects f
Super keys of a relation can have extra attributes. Candidate keys are minimal super key, i.e. such a key have no extraneous attribute. An attribute is known as extraneous if even
Database Manager It is the interface among low-level data, queries and application programs. Databases typically need a large amount of storage space. It is kept on disks, as
Lack of Redundancy We have talked about the problems of repetition of information in a database. Such repetition should be stay away as much as possible. Let us state once again t
List the requirements needed to design a trigger. The requirements are:- Specifying when a trigger is to be implemented. State the actions to be taken when the trigger im
Although, the essential features of E-R diagrams are enough to design many database situations. Though, with more difficult relations and advanced database applications, it is need
I have been given 8 differebt data warehouseing failure case studies. I need to question 4 questions for each
Attributes that are directly kept in the data base. For example, 'Birth date' attribute of a person. Derived Attributes that are not stored directly but can be derived
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