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NAT 5 Computing – Databases: Questions and Answers, Exams of Mobile Computing

Harvard UniversityMobile Computing

A comprehensive overview of database management systems (dbms), covering fundamental concepts such as database definitions, file types, relational databases, and sql queries. it delves into the advantages and disadvantages of various database systems, including paper-based and electronic databases, and flat-file databases. The document also explores key database components like primary and foreign keys, referential integrity, and data dictionaries, along with different types of relationships and validation techniques. it includes numerous questions and answers to test understanding of these concepts, making it a valuable resource for students learning about databases.

Typology: Exams

2024/2025

Available from 05/22/2025

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NAT 5 Computing – Databases questions
2025
What is a database? - A collection of related information about a set of persons or
objects ( can be physical or electronic)
What does DBMS stand for - database managment system
Disadvantages of paper databases - - very bulky/lots of space
-easy to misfile , lose or damage records
-data was often duplicated
-keeping records up to date was difficult and time consuming ( duplicated records
may be updated in 1 but ot the other)
Advatages of electronic databases - -searching, sorting and calculating operations
can be done much easier
-information is more easily available to users(less time to find)
-
Limitations of flatfile databases - -duplication of data
-data may be inconsistant
-insertion , deletion and update anomalies
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What is a database? - A collection of related information about a set of persons or objects ( can be physical or electronic) What does DBMS stand for - database managment system Disadvantages of paper databases - - very bulky/lots of space -easy to misfile , lose or damage records -data was often duplicated -keeping records up to date was difficult and time consuming ( duplicated records may be updated in 1 but ot the other) Advatages of electronic databases - -searching, sorting and calculating operations can be done much easier -information is more easily available to users(less time to find)

Limitations of flatfile databases - -duplication of data -data may be inconsistant -insertion , deletion and update anomalies

Why is restricted choice validation used - -eliminates input errors -so users are presented wiht the only options How do dates get sorted ( ASC and DESC ) - ASC oputs earliest dates first (12/1/ before 12/2/20) DESC puts latest dates first ( 12/2/20 before 12/1/20) What is data? - Raw unprocessed facts and figures What is information? - Data that has been processedand given meaning What is a file? - Collection of structured data on a particular topic What is a record? - A collection of structured data on a particular person or thing, a row in a table What is a field? - An area on a record which contains an individual piece of data , a column

In an ER diagram the primary key is ... - underlined In an ER diagram the forgien key is ... - stared ( * ) What is a data dictionary - a description of the structure of the data held in a database What sort of information can a data dictionary include - - field name -data type -size (text fields only) -key ( P or F) -validation required -sample data What are the types of validation - -presence check -length check -range check -restricted choice

What does SQL stand for - Structured Querry Language What are the 4 types of querries - -select -insert -update -delete What is a complex sort - a sort that depends on more than 1 field What is the structure of a select querry - SELECT "the field you want to display" FROM "the table name" WHERE "the condition that needs to be met" ORDER BY "field name" ASC/DESC How do you display all fields in a select statement - SELECT * How to select fields from 2 table - SELECT tablename.fieldname