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Explain Data Sublangauges ?
Data sublanguage: In relational database theory, the term sublanguage, first used for this purpose through E. F. Codd in the year of 1970, refers to a computer language used to describe or manipulate the structure and contents of a relational database management system (RDBMS). Typical sublanguages related along with modern RDBMS's are QBE (Query by Example) and SQL (Structured Query Language).
Define tuple variable? Tuple variables are used for comparing two tuples in the same relation. The tuple variables are explained in the from clause by way of the as clause.
Given the following set of functional dependencies {cf→ bg, g → d, cdg → f, b → de, d → c} defined on R(b,c,d,e,f,g) a. Is cf→ e implied by the FDs? b. Is dg a superkey?
Example RELATION SCHEMA for STUDENT: STUDENT (Roll No: string, name: string, login: string, age: integer) RELATION INSTANCE
What are the requirements to ensure the objectives of file management principle is realized?
Problem: You are given the following schema 1. Flights(flno, from, to, distance) 2. Aircraft(aid, flno, aname, cruisingRange) 3. Certified(eid, aid) 4. Employees(eid, ena
Define Atom of domain relational calculus An atom has the outline 1 , x 2 , ... , x n > -> r , in which r stands for a relation on n attributes and x 1 , x 2 , ... , x n ar
Relational and E-R Model There are three types of constraints on relational database that have: DOMAIN CONSTRAINT PRIMARY KEY CONSTRAINT INTEGRITY CONSTRAINT
What are the three data anomalies that are similarly to take place as a result of data redundancy? Can data redundancy be completely eliminated in database approach? Why or why n
During the deletion of a tuple two cases can happen: Deletion of tuple in relation having the foreign key: In this type of case simply delete the desired tuple. For example, in
Vertical Fragmentation- Vertical fragmentation groups together only those attributes in a relation that are used jointly by various important transactions. A vertical fragment is d
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