Information Systems

Question 1

List advantages of an information system?

Answer 1

Small amount of space.
Can be accessed quickly.
human error reduced.
A computer can deal with boring tasks.
Information can be made available to number of people simultaneously
Sophisticated electronic methods can be used to protect the information in a database.

Question 2

The essential characteristics of a relational database?

Answer 2

Data appears in tables.
The language used generates a new table as the result of a database operation.
Protected against undesirable user action.
Entities (fields) in the system have a relationship with at least one other entity.

Question 3

Basic Structure of a MSQL query?

Answer 3

Select
from
note: start every problem with these 2 lines.

Question 4

Definition of an information system?

Answer 4

it is a computerised record keeping system.

Question 5

What does SQL stand for?

Answer 5

Structured query language.

Question 6

How to eliminate duplicate (same type) rows?

Answer 6

A result table should show one listing for each result, with duplicate rows removed.
This is achieved by the use of the key word ‘distinct’

Question 7

How to order Column Data?

Answer 7

The order of the information appears in the way it was originally put into the table.
For example – The column pm_name in the table prime minister is ordered alphabetically. Adding the terms ‘order by’ will do this.

Question 8

Ordering several columns?

Answer 8

If more than one item is included in the order by clause, a comma must separate consecutive items. Rows are arranged in order so that the second item is in specified ordered within the first (or primary) ordering criterion.

Question 9

how to ‘order by’ with numbers?

Answer 9

Simply replace the column in the order by section by the number in what order it comes.

Question 10

Conditional Retrieval?

Answer 10

It is often necessary to retrieve only rows from the table which satisfies a given condition.

Question 11

Analysis Definition?

Answer 11

Analyse = tell what each line in the query does and break it down into smaller pieces and examine them.

Question 12

Comparison Operator?

Answer 12

Comparison Operator:
 = equal to
<> or ^= not equal to 
> greater than
^> not greater than
>= greater than or equal to
< less then 
^< not less than
<= less than or equal to

Question 13

Using the Null keyword? (is)

Answer 13

Note: The key word ‘is’ is not required in the query, it depends on your preference.

Question 14

Special Operators

Answer 14

Between, In, Like

Question 15

Between Operator?

Answer 15

Retrieval on values within a range. Rows may be selected if a column or derived values lie within a specific numeric or character range.

Question 16

In Operator?

Answer 16

Rows that contain a value which appears in a given list of constants may be retrieved with the ‘in’ operator.

Question 17

Like Operator?

Answer 17

Substring search capability. Certain characters have special meaning when used with the ‘like’ operator.
An underscore refers to any single letter/ character.
The percentage sign refers to any combination of zero or more characters.
Quotes must be placed around the pattern to be matched.