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Explain Domain calculus
Domain calculus is one of the types of the relational calculus. The formal specification of the domain calculus was planned after the development of the QBE system. Domain calculus has the variables range in excess of single value from domains of attributes. To create a relation degree n for a query result, we should have n domain variables - one for each attribute. An expression of the domain calculus is of the form {X | F(X)}
In which F is a formula on X and X denotes a set of domain variables. The expression characterizes X like F(X) is true.
What is a SELECT operation? The select operation selects tuples that please a given predicate. We use the lowercase letter σ to denote selection.
Task Part A. Create an ERD from a business problem. (50 marks) Read the following problem and complete the tasks listed below. THE ABS Blood Bank Australian Blood Services (ABS) i
Example: //REVOKE ALL ON EMP FROM MCA12; (All permissions will be cancelled) You can also cancel only some of the permissions. Drop: A user-
What is trigger Triggers are statements that are implemented automatically by the system as the side effect of a change to the database.
Foreign Keys and NULL Let us take the relation: DEPT DEPT ID DNAME BUDGET D1 M
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Determine the rule that a value of a foreign key should appear as a value of some particular table is called a Ans: Referential constraint. The rule that a value of a fo
Define Direct file organization? The direct file organization is employed to enhance the performance in accessing the records than sequential file organization. In direct file
You group has been hired by TrainingrUs.com to keeps track of training revenues. TrainingrUS.com wants you to keep scheduling. COURSE table contains following information:
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