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What do you mean through integrity constraints?
Integrity Constraints -An integrity constraint is a condition specified on a database schema and restricts the data in which can be stored within an instance of the database. If a database instance satisfies all the integrity constraints described on the database schema, it is a legal instance. A DBMS enforces integrity constraints, in which it allows only legal instances to be stored in the database.
In the ER diagram, one example of subclassing is depicted following the Services entity. The subclasses Item Based and Time Based are created. The entity Services gains the attribu
Briefly describe concurrency execution? Lock - based protocols Locks There are several modes in which a data item may be locked in this section we restrict our attention
What sorts of tables one can se in designing the hierarchy of a LDB? Tables, which are having Foreign Key relations.
What is OOM? Object oriented modeling is an approach by which modeling of systems is done by visualizing the system based on real world concepts. Object oriented modeling does
Describe integrity constraints? Integrity Constraints - A database is just as excellent as the information stored in it, and a DBMS must therefore help avoid the entry of inc
What are domain constraints? A domain is a set of values that might be assigned to an attribute .all values that appear in a column of a relation must be taken fro
#question benefits and limitations of data models..
Explain the concept of generalization and aggregation in E_R diagrams. Give one example for each one of them? Generalization: Consider extending the entity set account throug
Having Clause with sub queries: First we have to recollect the GROUP BYclause. The following query searches the minimum salary in every department. SELECT DEPTNO, MIN (SAL)
Use of partial data by applications : In common, applications work with views rather than whole relations. Thus, it may be more appropriate to work with subsets of relations rather
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