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Explain the concepts of relational data model?
Relational Data Model - The relational model was first introduced through Prof. E.F. Codd of the IBM Research in the year 1970 and attracted immediate attention because of its simplicity and mathematical foundation. The model uses the concept of a mathematical relation (such as a table of values) as its primary building block, and has its theoretical basis within set theory and first-order predicate logic. The relational model represents the database as a collection of relations. The relational model such as all other models consists of three basic elements:
Saving Derived Attributes to Avoid Re-computation As discussed, "redundancy means duplication of exact data". But, if multiple copies of same data are present in the system,
Name the metrics for selecting top algorithm There are a number of metrics for selecting top algorithm: i) Computational complexity: Computational complexity refers to eff
explain cascading rollback
Clustering Indexes It may be an excellent idea to keep data of the students in the order of the programme they have registered as most of the data file accesses may need studen
Databases and data warehouses both are databases and both contains number of rows and columns of tables containing data. Data warehouse is really different from databases because d
What is the use of with clause in SQL? The with clause gives a way of defining a temporary view whose explanation is available only to the query in which the with clause occurs
why are older data models are being replaced by new data models
If R1 and R2 are two union compatible relations or functions, then the result of R3 = R1 ∩R2 is the relation that contains all tuples that are in both the relations In other words,
Create a view emp_dep containing e_name and number of dependents from the tables employee and dependent of (i) CREATE VIEW emp_dept AS SELECT ename, COUNT(*) FROM employee, dep
We will explain here an example database application having COLLEGE database and use it in showing several E-R modelling concepts. College database remains track of faculty, Stu
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