Question

1. What is a DBMS? Briefly describe the components of a DBMS.
2. What are entity-relationship diagrams and how are they used? What symbol is used for a relationship? What is an associative entity? Provide an example.
3. What is cardinality, and what symbols do you use in the crow’s foot notation method?
4. What are data warehousing and data mining? How do businesses use these tools?

Answer 1

Answer 1.

DBMS (Database management system): In brief, A DBMS is a software package to manage the database. A database is a collection of data that is collected for future uses. Database management refers to the technology or software package to store, manipulate, manage and retrieve user's data with efficiency and security. For example, MySQL, Oracle, Foxpro, dBase are some of the well-known DBMS used everywhere.

Component of DBMS: Organization collects a lot of data of customers, competitors, and industry, and they use a database management system to collect, manage, retrieve and future use of data. There are so many components of a database management system that are briefly explained below:

• Software: This is one of the most important components of any database. The software helps in storing, managing, retrieving and manipulating data and also use in sharing the data from one user to another user via connectivity servers.
• Hardware: Hardware includes electronic devices, input-output, and storage devices and creates an interface between computers and users.
• Data: This is the most important component of the database management system. Data is called resource and for that databases are designed to store and manage the data that can be used for future purpose and analytics. The system will have both metadata and actual or operational data.
• Procedures: Procedures are the rules and guidelines for operating the database management system. Procedures help in designing the database and also helping in solving issues with DBMS. Procedures also help in setup the database, login, and logout from the database and to take backup.
• Database access language: These are the computer language to write and give commands to access the database. A user can create a new database and access the database by giving commands using database access language.

Answer 2.

Entity Relationship Diagram: Entity Relationship Diagram refers to a flowchart or relationship diagram that shows how people, object or concepts have a relationship with each other in a system. Here the system is referred to as a database or information system. Basically, an entity-relationship diagram work on data modeling techniques that help in defining business processes.

Entity Relationship Diagram is used in the following ways,

• Database Design.
• Information system
• Database troubleshooting
• Business process redesigning
• Education and Research

In the ERD diagram system, a diamond shape (symbol) is used for relationships between different entities. Single diamond means strong relationships and double diamond means a weak relationship in the ERD system.

Answer 3.

Associative Entity: Associative Entity is a concept and technique that is widely used entity-relationship and rational theory. Associative entity refers to the connections that explain the relationship between two different entities in a database system. There are so many events and transactions are available in any system. When any event or transaction that have own set of attributes and those entities or transactions are linked in a many-to-many relationship is called associative entity. Basically associative entity explains the information of their attributes and connections.

One of the best examples to understand the Associative entity is a call center. There are so many phone calls between customer care executives and customers. A customer care executive can have many calls with customer and in such a way a customer can have many calls with customer care executives. This relationship is called a many-to-many relationship and the system that tracks this relationship is called the associative entity.

Another example could be to post on social media platforms by users. A post on social media can be commented on by so many users and so many users can comment on many other posts. This relationship and system are called an Associative entity.

4. Cardinality refers to the uniqueness of the data in a database. It is basically a number or quantity of unique values in a data table. For example, for a database where a data column is a Gender, in this column, there would be 2 data sets that are male and female. High cardinality means that the data column contains more percentage of unique values and vise versa. This is the definition we use in SQL.

There is one another meaning of cardinality in data modeling. Cardinality is the relationship between the number of attributes that can be related to other entities in database management. It represents the relationship of one table to another table in datasets. The relationship could be one-to-one, one-to-many, many to many or many to one.

In crow's foot notation concept, entities are represented by rectangle boxes with its name on the top.

The relationships between entities (boxes) are represented as lines.

Crow's foot notation is a relationship concept that used to show cardinality between entities. There are four symbols are used in crow's foot notation that is as follows,

• Two vertical lines on the line between 2 entities - show one and only one relationship.
• Crow's footnote and vertical line - show One or many.
• Crow's foot and circle- Zero or one or many relationships.
• Vertical line and circle- shows zero or one relationship.