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What is inheritance? Define it in detail?
Inheritance
Inheritance can be at the levels of types, or at the level of tables we first consider inheritance of types, then inheritance at the level of labels.
Type inheritance
Assume that we have the following type definition for people
create type person
(name varchar(20)
address varchar(20))
Table inheritance
Create table people of person
The consistency requirements for sub tables are
1. Each tuple of the sub table can correspond to at most single tuple in each of its immediate sub tables.
2. SQL:1999 has an additional constraint that all the tuples corresponding to each other must be derived from single tuple .
Domain Constraint It shows that each attribute in a relation has to contain an atomic value only from the corresponding domains. The data types associated with commercial RDBMS
Illustration of implementation of inheritance Let us take the illustration of implementation of inheritance. Suppose that we are about to implement the Stack class and by now w
What is meant by heuristic optimisation?Discuss the major heuristics that are applied during query optimisation.
Use a Set operator to create a list of academics who have written or co-written less than 5 papers and also have greater than 3 interests. List their academic number in the output.
1. Item based services will be charged fixed prices, and time-based will be charged variably depending on time. Such as per hour. Item-based: Fixed, pedicure, waxing, threading, fa
The physical location of a record is determined by which mathematical formula that transforms a file key into a record location? The physical location of a record is determined
Control as a State Machine Engine First let us define the state machine: "the state machine is a machine which is an object but not an application object. It is a part of lang
Example- Search the salary of employees who are not 'ANALYST' but get a salary below than or equal to any people employed as 'ANALYST'. SELECT EMPNO, ENAME, JOB, SAL FROMEMP
What are the uses of functional dependencies? To test relations to see whether they are legal under a given set of functional dependencies. To state constraints on the set
Database systems have many opposite efforts ?
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