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Update Operations and Dealing with Constraint Violations
There are three basic operations to be executes on relations:
The INSERT Operation:
The insert operation permits us to insert a new tuple in a relation. When we try to insert a new record, then any of the following four types of constraints can be violated:
• Entity Integrity constraint: If the primary key attribute value of new tuple t is given as null.
What is nested relational model? The nested relational model is an extension of relational model in which domains might be either atomic or relation valued.
What is a Phantom Deadlock? In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to recognize deadlocks
Explain several types of constraints that can be specified using CREATE TABLE command. Explain CASCADE and RESTRICT clauses of DROP SCHEMA command? Constraint Description PRIM
Describe the term- State Diagram State Diagram: An object could receive a sequence of the input instructions. The state of the object can differ depending upon sequence of in
Define single valued and multivalued attributes. Single valued attributes: attributes with a single value for a particular entity are known as single valued attributes. Mult
What are stored and derived attributes? Stored attributes: The attributes keeps in a data base are known as stored attributes. Derived attributes: The attributes that are de
Object-based Models: Use objects as key data representation components . Examples:- Entity-Relationship Model: It is a collection of real world objects known as entitie
If the insertion violates one or more constraints, then two alternatives are available: Default option: - Insertion can be discarded and the reason of refusal can also be ex
What is an index? An index is a structure that helps to place desired records of a relation quickly, without probing all records.
Consider the following frequency counts of some itemsets in a transaction database r : freq({A}, r) = 0.405 freq({B}, r) = 0.510 freq({C}, r) = 0.303 freq({A
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