Databases - Introduction

Question 1

What is a Flatfile DB?

Answer 1

A database that consists of only one table.

Question 2

What are the issues with Flat file DBs?

Answer 2

In larger databases they cause problems such as:

• repeating data
• increased file sizes
• insert-update-delete anomalies

Question 3

Name and describe the three anomalies

Answer 3

• INSERT - inability to insert data to the database due to the absence of other data.
• UPDATE - the same data is repeated in multiple rows, and changes are made in some but not all instances.
• DELETE - inability to delete data from the table without having to delete the whole record.

Question 4

How can we avoid anomalies?

Answer 4

By designing relational DBs that use two or more linked tables to store data.

Question 5

Name the 5 field types

Answer 5

• TEXT - including numbers starting with a zero and punctuation
• NUMBER - decimals included
• DATE
• TIME
• BOOLEAN - yes or no , true or false, etc.

BOB NEVER TWO TIMES DATES

Question 6

What is a primary key?

Answer 6

A field that is used to uniquely identify every record in a database

Question 7

What is a foreign key?

Answer 7

Primary key from one table that appears in another table to link the two together.

Question 8

What is a field?

Answer 8

Smallest unit of storage in a database

Question 9

What is a record?

Answer 9

Column of values, usually belonging to a particular field.