8.1 Database concepts

8.1 Database Concepts

A Database is a structured collection of items of data that can be accessed by different applications programs.

Fill in the Blanks

What is a structured collection of items of data that can be accessed by different application programs?

Why not use file-base system?

• Data Redundancy (Duplication)

• Data Inconsistency

• Lack of Data Integration (no connections)

• Limited Data Access (format)

• Difficulty in Managing Security

Multiple Choice

Is a file-based system a good method for storing organizational data?

• Yes

• No

Fill in the Blanks

What is a database in which the data items are linked by internal pointers?

• Efficient storage: Data is stored only once, minimizing redundancy.

• Consistency: Changes in one application are reflected across others, ensuring data consistency.

• Data independence: Queries are not affected by the data structure or the software used.

Multiple Choice

What is the best method for storing data in a computer system?

• File-based system

• Database

• Write it by hand on a piece of paper.

• Write the data in your hand.

Labeling

Label the different key words of a database.

Drag labels to their correct position on the image

record

table

field

Drag and Drop

A ​

Placeholder

is a group of similar data, in a ​

Placeholder

, with rows for each instance of an entity and columns for each attribute. A ​

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is a row in a table in a database. A ​

Placeholder

is a column in a table in a database.

Drag these tiles and drop them in the correct blank above

table

database

record

field

​A	A PROFESSIONAL says​
​Table	Entity​
​Record	Tuple​
​Field	​Attribute

• ​Data is shared between applications using a database.

• To ensure data consistency and integrity the updating is control using transactions and also it is automatically updating using the pointers.

• Pointers (keys) between tables minimize data duplication and establish relationships between them.

Fill in the Blanks

What is an attribute or smallest set of attributes in a table where no tuple has the same value?

Fill in the Blanks

What is a unique identifier for a table and a special case of a candidate key?

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What is a candidate key that serves as an alternative to the primary key?

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What is a set of attributes in one table that refers to the primary key in another table?

​Relationships can take several forms:

» one-to-one, 1:1

» one-to-many, 1:m

» many-to-one, m:1

» many-to-many, m:m.

8.1.4 Entity-relationship (E-R) diagrams

Labeling

Label.

Drag labels to their correct position on the image

one or many

zero or many

one

many

zero or one

one (and only one)

8.1.5 The normalisation process

​Normalisation is used to construct a relational database that has integrity and in which data redundancy is reduced.

8.1.5 The normalisation process

Example of bad practice:

8.1.5 The normalisation process

First normal form (1NF) - entities do not contain repeated groups of attributes.

8.1.5 The normalisation process

First normal form (1NF) - entities do not contain repeated groups of attributes.

8.1.5 The normalisation process

Second normal form (2NF) – entities are in 1NF and any non-key attributes depend upon the primary key. There are no partial dependencies.

8.1.5 The normalisation process

Third normal form (3NF) – entities are in 2NF and all non-key attributes are independent. The table contains no non-key dependencies.

8.1.5 The normalisation process

Third normal form (3NF)