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Define the Query optimisation
The query parser commonly generates a standard initial tree to correspond to an SQL query, with no doing any optimization. Such type of a canonical query tree denotes a relational algebra expression that is extremely inefficient if executed directly. A query commonly has many possible execution strategies, and the process of choosing a appropriate one for processing a query is termed as query optimization. The major guidelines that are applied throughout query optimization are:
a. Combine a cascade of selections
b. Combine a cascade of projections
c. Commute selection and projection
d. Commuting selection with join / cartesian product Commuting projection with join or cartesian product
e. Commute projection with set operations
f. Commute selection with set operations
Before defines the second type of integrity constraint, viz., Entity Integrity, we should be well-known with the concept of NULL. Mostly, NULL is intended as a basis for dealing
What is a dataset? A dataset is an in-memory database that is disconnected from any regular database, but has all the significant characteristics of a regular database. Dataset
Problem 1. Write the SQL queries using Data Manipulation Language (DML) statements. Insert values into student table with field names using insert command Display the
Submission Requirements All answers must be computer generated (including text and diagrams). The hand-in version must include a header page (or with sufficient space)
Explain in details about Data Sharing
why are older data models are being replaced by new data models
a) Distinguish between ‘database' and ‘Database Management Systems (DBMS)'. b) List and briefly describe five potential benefits of the database approach compared to conventio
It is mandatory that for every table in the LDB hierarchy there should exist one GET statement in the report. False. It is not essential.
Physical Records These are the records that are stored in the secondary storage devices. For the database relation, physical records are the group of fields kept in adjacent me
external and internal mapping with examples
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