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Define the five basic operators of relational algebra?
Five basic operators of relational algebra are:1. Union (∪∪∪∪) - Selects tuples which are in either P or Q or in both of them. The duplicate tuples are eliminated.R = P ∪ Q2. Minus (-) - Removes generally common tuples from the first relation.R = P - Q3. Cartesian Product or Cross Product (××××) - The cartesian product of two relations is the concatenation of tuples belonging to the two relations and consisting of all probable combination of the tuples.R = P × Q 4. Projection (ππππ) - The projection of a relation is described as a projection of all its tuples over a few set of attributes, i.e., it yields a vertical subset of the relation. It is used to either decrease the number of attributes (degree) in the resultant relation or to reorder attributes. The projection of a relation T on the attribute A is denoted through πA(T).5. Selection (σσσσ) - Selects only some of the tuples, those satisfy given criteria, from the relation. It yields a horizontal subset of a given relation, i.e., the action is defined over a complete set of attribute names but just a subset of the tuples are involved in the result.R = σB(P)
Give the reasons for allowing concurrency? The reasons for allowing concurrency is if the transactions run serially, a short transaction might have to wait for a preceding long
Question: (a) Use the following business rules to produce the E-R diagram. You should clearly show all the minimum and maximum cardinality constraint on each side of the relati
Define the Boyce-Codd Normal Form with instance and also Compare BCNF and 3NF. Ans: BCNF: For each functional dependency X->Y in a set F of functional dependencies over relati
Write short notes on tuple relational calculus. The tuple relational calculation is anon procedural query language. It defines the desired information without giving a particul
What is the main difference between read-only and update methods? A read-only method does not affect the values of a variable in an object, whereas an update method may alter t
need a DBMS system on any data for assignment.
What are the factors to be taken into account when choosing a RAID level? A) Monetary cost of extra disk storage requirements. B) Performance requirements in terms of number
What is the most significant feature that does not directly map into programming language structures? Why? Association, since there are complex types of association, like as qu
Define the concept of Object Diagram An object diagram shows a set of the objects and their relationships with each other at a point of time. In a static view, object diagram
What is known as heap file organization? In the heap file organization, any record can be placed anywhere in the file where there is space for the record. There is no ordering
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