While developing new softwares or databases, several modelling concepts play a crucial role to offer structures and give ideal information to the users.
One such concept is called the cardinality in DBMS!
This is touted as the concept that helps all the users to describe two differential objects which are related to each other.
Understanding cardinality will help you understand databases and to organise your business data while increasing overall information efficiency.
To help you in this regard, we have curated this blog post!
Here, we are going to study in-depth about the cardinality in DBMS.
Without any delay, let’s get started!
What is cardinality in the DBMS?
Cardinality is defined as a mathematical term which refers to the elements of certain sets in the database. A database administrator can make use of the cardinality for counting tables and their values.
In the database, it represents the relationship between two different data tables while highling the number of times any entry occurs in the comparison of each other.
For instance; an auto repair shop has a database which shows that any mechanic works with numerous customers on a daily basis. It shows the relationship of a mechanic working with his multiple customers.
In the example, you can note down that each customer will have only one vehicle they bring to the shop while visiting. This means that the relationship would be a one-on-one relationship.
With the help of cardinality, administrators can efficiently manage these relationships in a software or a program.
This will make it easy for them to see the entire correlation between the mechanics, their customers and the cars when they search for any kind of data related to it.
Importance of cardinality in database
Cardinality in DBMS plays a key role as it creates links from any table or entity to the other in a structured manner.
This will make a significant impact on a query with the sequence of steps that a user can take to search or to access data in a database system. With a well-structured execution plan, it will become way easier to locate the data as and when needed.
The database administrators can also apply cardinality for a variety of reasons, but businesses mainly use this model in order to analyse all the information related to the customers.
For example; the online retailer has a database table with the lists of all its unique customers. It may also have some other database with the lists purchased by the customers from the store. As all customers purchase multiple items from the store, you can represent it in the form of patterns or by expressing their cardinality relationship by linking each customer with that of the tables.
Type of cardinalities
When you talk about cardinalities, they are mainly classified into three types which are discussed as follows:
- One-to-one relationship: This relationship describes a particular situation where an occurrence of an entity may relate to the occurrence of another entity. If you are working with the specific row or table, you may use this type of cardinality.
- One to many relationships: It describes the situation where an occurrence in the entity is related to multiple occurrences of another entity. If you are working with one row in a given table which is related to multiple rows in the different table, you may see this kind of cardinality
- Many to many relationships: This one describes the relationship where the multiple occurrences in a single entity can be related to the multiple occurrences with the other entity. If you are working with the several rows of a table with several rows of another table, you will see this type of cardinality.
High and low cardinality
When you are on the subject, you should know about the high and the low cardinality. A column which is populated with some of the distinct values is touted as the high cardinality column.
While the low number of the distinct values in any column will make it a low cardinality column. While selecting any column with the index or using it as a base for the partition key, you can look for its high cardinality counterparts.
Moreover, a database query will also use the available index if the columns contain some distinct values. Moreover, in terms of your database performance, any low cardinality column will result into the full scan operations which can be expensive in this case.
Cardinality and the modality
When you measure the number of associations in between two or more rows and columns, you can use the term cardinality. The focus here would be on the maximum associations.
Though, the modality focuses on the minimum relationships between the table rows and entities. The modality in the relationship would be 0 in the case a relationship is considered optional, while any other modality would be 1 if the occurrence of that relationship is considered mandatory.
Cardinality in the time series database
In the time series database, you would be able to see the applications of cardinality. It mainly refers to the numbers in a time database series. A time series is touted as the set of values over the given period of time which will be stored as the pairs.
There would be a data model that may start from the points to give you the desired value. You can use the monitoring system in order to find exact values.
Anomalies in DBMS
When we are talking about DBMS, another crucial concept every aspirant should learn is Anomalies in DBMS. An anomaly is like some unwanted situation which can impact the whole database inconsistency. You can use it to remove redundancy.
Wrapping Up
Read this blog and take cues from it to learn in detail about the cardinality in DBMS. This is a sought yet a very crucial DBMS concept that is often asked from the aspirants.
Learn from this blog and build a strong foundation related to this topic!
Happy learning!
