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What are the General Transformation Rules for Relational operations?
Ans: The transformation rules transform one relational algebra expression to AN
EQUIVALENT ONE
1. Employed by the query optimizer to optimize query tree
2. Any type of rule, if applied, ensures that the resultant tree is equivalent → resulting execution plan is equivalent
General Transformation Rules is as follow:
1. Commutativity of s: The s operation is commutative:
Explain algorithm of ER To Relational Mapping ? ER-to-Relational Mapping Algorithm: 1) Step 1: Mapping of regular entity types: For each strong entity type E, form a relatio
While using extract datasets it is required to have a special workarea for interface False. It is not required to have a special workarea for interface
Differentiate between natural join and outer join? Natural join is a binary operator which is written as (R * S) where as R and S are relations. The output of the natural join
Using a database design approach of your choice, produce a logical design for Pharma. 1) Your answer must consist of ONE the following: An entity-relationship (ER) diagra
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.
Consider the subsequent relations for a database which keeps track of business trips of salespersons in a sales office: SALESPERSON (SSN, Name, start_year, Dept_no) TRIP (SSN, Fr
Removing a Synonym: DROP SYNONYM D30;
ER diagram on cosmetics
What are the disadvantages of relational data ? Disadvantages • Performance - If the number of tables among that relationships to be established are large and the tables t
What is a homogeneous distributed database? In homogeneous distributed databases, all sites have the same database management system software, are aware of one another, and agr
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