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Define Partial Key and Primary Key
A partial key, also known as discriminator, is the set of attributes which can uniquely identify weak entities that are related to similar owner entity. Primary key is a unique key but not comprise null values. An entity set can comprise at most one primary key.
Differentiate between Key and superkey? Key and superkey - A key a single attribute or a combination of two or more attributes of an entity set in which is used to identify o
Define the concept of aggregation. Give two examples where this concept is useful. Ans: Aggregation transforms a relationship among the objects into a higher-level object. A
1 NF Normal Form The domain of attribute must add only atomic (simple, indivisible) values First normal form (Minimal Form or 1NF) is a normal form need in database normalizat
What is the difference between a key and a superkey? Key - A key a single attribute or a combination of two or more attributes of an entity set which is used to identify one
Domain Constraints Domain constraints are primarily formed for defining the logically correct values for an attribute of a relation. The relation allows attributes of a relatio
we need example of 2phase locking
What are the purpose for having variable length records? What kinds of separator characters are required for each? Variable-Length Records - Variable-length records are thos
Information about a bank is about customers and their account. Customer has a name, address that consists of house number, area and city, and one or more phone numbers. Account ha
The primary key is selected from the
To eliminate duplicate rows (distinct operator) Example: SELECT DISTINCT DEPTNO FROM EMP;
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