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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 .
, write the relational schema, and draw the new dependency diagrams. Identify the normal forms for each table structure you created
What is meant by computing the closure of a set of functional dependency? The closure of F denoted by F + is the set of functional dependencies logically implied by F.
CREATE TABLE prodtrans ( pno number (4) ptype char (1) CHECK (ptype in ('I','R','S')), qty number (5) FOREIGN KEY pno REFERENCES product (pno) ON DELETE CASCADE);
Consider the following relations: S (S#, SNAME, STATUS, CITY) SP (S#, P#, QTY) P (P#, PNAME, COLOR, WEIGHT, CITY) Give an expression within SQL for each of queries b
There are three main sources of utilities and applications for a DBMS: a. Vendor applications and utilities are given for working with or maintaining the database, and generally
Define data model? A data model is a collection of conceptual tools for explaining data, data relationships, data semantics and consistency constraints.
What is trigger? Triggers are statements that are executed automatically by the system as the side effect of a modification to the database.
Define identify relationship? Identifying relationship: An identifying relationship means in which the child table cannot be uniquely recognize without the parent. For exampl
Record based Logical Models: Use records as the key data representation components Examples: Relational Model: It shows data as well as relationship between data in the form
The Transactions- A transaction is definite as the unit of work in a database system. Database systems that deal with a huge number of transactions are also termed as transaction p
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