Teminology

Question 1

Data

Answer 1

Values stored on paper, in a person’s mind or stored in a database.

Question 2

Information

Answer 2

Data values that have been processed in some way to provide meaning. Information is Knowledge!

Question 3

Null

Answer 3

A value is Not Known or Not Applicable. Nulls are the “bane” of a programmers existence as Null compared to any value in a mathematical operation will always result in (return) a Null.

Question 4

Table

Answer 4

In the initial design phase you identify the “things” of significance to the business. These “things” will probably become tables in your database.

Question 5

Field

Answer 5

These are the qualities or characteristics of the entities. A field typically contains a single (scalar) value. Although there is a data type that supports multiple values called an array.

Question 6

Calculated Field

Answer 6

Contains a value resulting from a calculation of other stored values, such as: Qty * Price.

Question 7

Data type

Answer 7

Scalar Data types include characters (text), numbers, dates, boolean (Yes, No or True, False).

Question 8

Record

Answer 8

All the characteristics that quantify a single instance of the entity. Tuple is an academic term that means an ordered list of a specified type.

Question 9

View

Answer 9

A view is not a physical object it is a SELECT statement based on one or more underlying physical tables. The view SQL Statement is stored in the database data dictionary.

Question 10

Materialized View

Answer 10

Is a physical object which contains all the data from the underlying base tables – current to the point in time the snapshot was “taken”.

Question 11

Primary Key

Answer 11

A special field or group of fields that are used to uniquely identify each record in a table.

Question 12

Foreign Key

Answer 12

A field or group of fields that are used to relate 2 tables together. WHERE employees.EmployeeId = departments.EmployeeId.

Question 13

Unique Key

Answer 13

Indicates a field that must store a unique value for each record in the table or else be null.

Question 14

Index

Answer 14

Is a physical object which is used to speed up processing of query results and is also used to maintain the Primary and Unique Key constraints.

Question 15

Relationship

Answer 15

Perhaps the most important term in Database Design. The 3 relationship types are One-to-One, One-to-Many and Many-to-Many. Discussed further below.

Question 16

Degree

Answer 16

A relationship must be quantified as to whether it is a MUST BE (Mandatory) or a MAY BE (Optional). Discussed further below.

Question 17

Linking Table

Answer 17

The Many-to-Many relationships cannot be built in a Relational Database model. A Linking table is used to resolve this problem. Discussed further below.

Question 18

Field Specification

Answer 18

At a minimum a field must have a name, a data type and length. LastName CHAR(15).

Question 19

Data Integrity

Answer 19

Data must be valid, consistent and accurate or its’ values may be misleading.