Question 1. When Is A Functional Dependency F Said To Be Minimal?
- Every dependency in F has a single attribute for its right hand side.
- It cannot replace any dependency X –>A in F with a dependency Y–> A where Y is a proper subset of X and still have a set of dependency that is equivalent to F.
- We cannot remove any dependency from F and still have set of dependency that is equivalent to F.
Question 2. What Is Operational Data Store?
An operational data store (or “ODS”) is a database designed to integrate data from multiple sources to make analysis and reporting easier.
Question 3. What Is Multivalued Dependency?
Multivalued dependency denoted by X–>Y specified on relation schema R, where X and Y are both subsets of R, specifies the following constraint on any relation r of R: if two tuples t1 and t2 exist in r such that t1[X] = t2[X] then t3 and t4 should also exist in r with the following properties
- t3[x] = t4[X] = t1[X] = t2[X]
- t3[Y] = t1[Y] and t4[Y] = t2[Y]
- t3[Z] = t2[Z] and t4[Z] = t1[Z]
where [Z = (R-(X U Y)) ]
Question 4. What Is Ddl (data Definition Language)?
A data base schema is specified by a set of definitions expressed by a special language called DDL.
Question 5. What Is Vdl (view Definition Language)?
It specifies user views and their mappings to the conceptual schema.
Question 6. What Is Degree Of A Relation?
It is the number of attribute of its relation schema.
Question 7. What Is A Relation Schema And A Relation?
A relation Schema denoted by R(A1, A2, ?, An) is made up of the relation name R and the list of attributes Ai that it contains. A relation is defined as a set of tuples. Let r be the relation which contains set tuples (t1, t2, t3, …, tn). Each tuple is an ordered list of n-values t=(v1,v2, …, vn).
Question 8. How Does Tuple-oriented Relational Calculus Differ From Domain-oriented Relational Calculus?
The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL
The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE.
Question 9. What Is Relationship?
It is an association among two or more entities.
Relationship Set – The collection (or set) of similar relationships.
Relationship Type – Relationship type defines a set of associations or a relationship set among a given set of entity types.
Degree of Relationship Type – It is the number of entity type participating.
Question 10. What Is Normalization?
It is a process of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to achieve the properties.
- Minimizing redundancy
- Minimizing insertion, deletion and update anomalies.
Question 11. What Is Functional Dependency?
Functional dependency is denoted by X –> Y between two sets of attributes X and Y that are subsets of R specifies a constraint on the possible tuple that can form a relation state r of R. The constraint is for any two tuples t1 and t2 in r if t1[X] = t2[X] then they have t1[Y] = t2[Y]. This means the value of X component of a tuple uniquely determines the value of component Y.
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