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Determine the Three Views of Data
We know that the similar thing, if viewed from dissimilar angles produces difference sights. Similarly, the database that we have formed already can have different aspects to reveal if seen from dissimilar levels of abstraction. The term Abstraction is very significant here. Generally it means the amount of detail you want to hide. Any entity can be seen from dissimilar perspectives and levels of complexity to make it a reveal its current amount of abstraction.
In the same manner, the database can also be viewed from dissimilar levels of abstraction to reveal dissimilar levels of details.
Primary index A primary index is a file that has a sorted series of records having two columns: a block address for that key field in the data file; and the ordering key field.
A View may be defined of as a virtual table, that is, a table that does not really exist in its own right but is instead inferred from one or more underlying base data table. T
Define a view and a trigger. Construct a view for the above relations that have the information about suppliers and the elements they supply. The view holds the S#, SNAME, P# , PNA
What is assertion? Mention the forms available. An assertion is a predicate expressing a condition that we wish the database always to satisfy. Domain integrity constraints.
Update Anomaly : This anomaly is occurred due to data redundancy. Redundant information makes updates more complex since, for example, varying the name of the instructor of MCS-014
Example : Search the name, department number and salary of employees drawing minimum salary in that department. SELECT ENAME, SAL, DEPTNO FROM EMP WHERE SAL IN (SELECT MI
Examples:- Hierarchical Model: It tells data as and relationships by hierarchy of data values. Figure illustrates an example of hierarchical model. Now a day's these models are
Define null values. In some cases a certain entity may not have an applicable value for an attribute or if we do not know the value of an attribute for a certain entity. In the
Data Mining 1. What is data mining? Write Data Mining applications. 2. Explain OLAP? Write the benefits of OLAP. 3. What are the key features of a Data Warehouse? 4. W
What is called as an N-way merge? The merge operation is a generalization of the two-way merge used by the standard in-memory sort-merge algorithm. It merges N runs, so it is k
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