Relational Databases

Question 1

What is a database?

Answer 1

A database is a structured way to store data so that it can be retrieved using queries

Question 2

What is the table?

Answer 2

The table is the structural format in which data is stored in a database

Question 3

What is record?

Answer 3

A record is a row in a table. It is all the data stored as part of the same overarching value.

Question 4

What is a field?

Answer 4

A field is a column in the table. These are the different categories storing values of different records

Question 5

What are the data types?

Answer 5

Integer (Whole number)
Real (Number with decimal component)
Datetime (Stores dates and times)
Char (Fixed length string up to 8000)
Varchar (Variable length string up to 8000)
Text (Variable length string up to 2GB)

Question 6

What is a primary key?

Answer 6

A primary key is a field that stores unique data for each record in a table.

Question 7

How does a relational database eliminate data inconsistencies and redundancies?

Answer 7

A relational databases make use of multiple tables linked by relationships.
Using relational databases and multiple tables allows the elimination of data redundancy and reduces data inconsistencies

Question 8

What is the purpose of the SELECT function?
Example?

Answer 8

SELECT… (list the fields to be displayed)
This function selects which field needs to be selected

SELECT MemberID, FirstName, Surname
FROM members

Question 9

What is the purpose of the FROM function?
Example?

Answer 9

FROM… (specify the table name)
This function assigns the table in which data is selected from

SELECT MemberID, FirstName, Surname
FROM members

Question 10

What is the purpose of the WHERE function?
Example?

Answer 10

WHERE… (list the search criteria)
This function is used to select on records that specify a condition

SELECT FirstName, Surname
FROM members
WHERE Town = ‘Ipswich’

Question 11

What is the purpose of the ORDER function?
Example?

Answer 11

ORDER BY… (Order in which the data outputted is to be)
This function allows a query to sort data by ascending or descending order

SELECT *
FROM members
ORDER BY Surname ASC

Question 12

How do you insert data into a table using SQL?

Answer 12

INSERT INTO (Table Name) (Fields)
VALUES (Value1, Value2)

Question 13

How do you edit and delete data in a database using SQL?

Answer 13

UPDATE (Table Name)
SET (FieldName = Changed Value)
WHERE (Search Criteria)

DELETE FROM (Table Name)
WHERE (Search Criteria)

Question 14

What are the issues with flat-file databases?

Answer 14

This leads to inconsistencies in the data making it hard to search and sort data.
Creates redundant data so the database uses more memory than needed