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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 attribute of R after that A cannot accept null values.
Referential Integrity Rule- In referential integrity, it is made sure that a value that appears in one relation for a given set of attributes as well appears for a particular set of attributes in another relation.
In SQL, referential integrity and entity integrity rules are implemented as constraints on the relation known as reference Key constraint and primary Key constraint correspondingly.
These constraints can be fixed with relation at the time of creation of the relations or after the creation of the relations by altering the definition of the relations. For instance:
What is first normal form? The domain of attribute must contain only atomic (simple, indivisible) values.
What is Trigger? Trigger: A database trigger is procedural code which is automatically executed in response to specific events on a particular table in a database. Triggers can
Explain the term- Periodic recomputation Periodic recomputation: Base values are often updated in bunches. Sometimes, it is possible to just recompute all derived attributes p
How does Oracle act as ODBC and give examples of front end uses with ODBC? ODBC achieve portability at the level of the executable by introducing an extra level of indirection.
what problems are raised by the database? why is it so controversial? why is data quality an issue?
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Define outer union operation of the relational algebra. Compute the outer union for the relations R and S given below. Outer Join - If there are any values in one tabl
What are partial, alternate,, artificial, compound and natural key? Partial Key: It is a set of attributes that can uniquely recognize weak entities and that are related to s
intent locking
QUESTION (a) Consider a car database consisting of car model, car make, car origin, Engine capacity, color, cost.
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