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What do you mean by atomicity and aggregation?
Atomicity: Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete transactions. DBMS ensures this by undoing the actions of incomplete transactions.
Aggregation: A concept which is used to model a relationship among a collection of entities and relationships. It is used when we require to express a relationship between relationships.
prototype of a distributed information system for a national car part retail outlet chain.
diagrams and meaning
, write the relational schema, and draw the new dependency diagrams. Identify the normal forms for each table structure you created
What are the different integrity constraints in RDBMS? The various integrity constraints in RDBMS are as: Primary Key: primary key is a grouping of one or more attributes
Define canonical cover? A canonical cover Fc for F is a set of dependencies like F logically implies all dependencies in FC and Fc logically shows all dependencies in F.
What are the various states through which a transaction passes through in its lifetime? Briefly discuss all the events that causes transition from one state to another. Ans:
Two Phase Locking (2PL) The two-phase locking protocol having of two phases: Phase 1 : The lock acquisition phase : If a transaction T needs to read an object, it wants to
We define a view in SQL through using the create view command. To describe a view, we must provide the view a name and must state the query in which computers the view. The form of
Define the terms i) DDL ii) DML DDL: Data base schema is particular by a set of definitions expressed by a special language known as a data definition language. DML: A data
Define entity integrity and referential integrity. How does SQL allow specification of these? Ans: Entity Integrity Rule- If the attribute A of relation R is a prime attribut
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