Last Updated on March 23, 2023 by Prepbytes
An aggregation is a type of association in which objects are assembled or configured to form a more complex object. An aggregation describes a collection of objects and how they interact with one another. It is also a process in which a single entity does not make sense in a relationship and one cannot infer results from that relationship, so the relationship of one or more entities acts as one entity. It can also be defined as a procedure for combining multiple entities into a single one. Aggregation in dbms is used to model relationships between entities and other relationships.
What is Aggregation in DBMS?
Aggregation in DBMS (Database Management System) is the process of combining two or more entities to form a more meaningful new entity. When the entities do not make sense on their own, the aggregation process is used. A relationship is established and the resulting product is created into a new entity in order to create aggregation between two entities that cannot be used for their individual qualities. The relationship can be of any type, such as SUM, AVG, AND, OR, and so on. Aggregation on tables can be done with a variety of tools available on the market.
When using numerical values as data, the following operations can be used to perform DBMS aggregation:
- AVG: This function returns the mean or average of the data values.
- Sum: After the data values have been added, this function returns a total value.
- Count: This field returns the number of records.
- Maximum (Max): This function returns the greatest value from a given set of data.
- Minimum (Min): This function returns the smallest value in a given set of data.
Example of Aggregation in DBMS
Assume a patient has visited a doctor in the hospital to seek treatment for a specific type of illness. The process flow for aggregation in the hospital is depicted in the diagram below.
We will use the simple ER model described above. There are three entities in the diagram above: patient history, doctor, and patient. Filing and diagnosis are examples of relationships. The patient is diagnosed by the doctor.
The database stores information about this diagnosis as well as any other patient information. Filing is required to make it easier for the doctor to retrieve the patient’s information in the future. In this case, the patient is unable to work alone. To get a diagnosis, he needs to build a relationship with the doctor. A diagnosis cannot be made by the doctor without the presence of the patient. In the future, the doctor will need information about the patient’s history, which he will have to gather from a filing system.
The final entity (the patient’s history) ensures that the system as a whole is operational. Without a doctor’s diagnosis and a filing system, obtaining the patient’s history is impossible.
When Aggregation in DBMS is Used?
Aggregation in dbms is used when you need to summarize or analyze data from a database. Some common use cases for aggregation in DBMS include:
- Generating reports: Aggregation functions can be used to summarize data and generate reports for various business purposes.
- Business intelligence: Aggregation functions are used in business intelligence applications to analyze large datasets and extract insights.
- Statistical analysis: Aggregation functions can be used in statistical analysis to calculate measures of central tendency, such as the mean, median or mode.
- Data visualization: Aggregated data can be visualized in charts and graphs to provide a better understanding of the underlying trends and patterns.
- Many insignificant entities: A DBMS may contain many insignificant entities that do not provide meaningful information. In this case, the trivial entities can be aggregated into a single complex entity. For example, many insignificant entities known as rooms can be combined to form a single entity known as a hotel.
Conclusion
In conclusion, we can conclude that aggregation in dbms (database management system ) is the process of computing a summary value for a set of data. which these function such as SUM, AVG, MIN, MAX, or COUNT, which operate on a column of data.
The aggregation function is applied to a group of rows in a table that satisfies a certain condition specified in the query, such as a WHERE clause. The result of the aggregation function is a single value that represents the summary of the group of rows.
Aggregation can also be used to group data by categories and provide summary statistics for each group. Aggregation in dbms is an important part of data analysis and reporting, as it allows for the efficient calculation of summary statistics on large datasets.
Frequently Asked Questions(FAQs)
Here are the FAQs on aggregation in dbms:
Q1. What are some common aggregation functions in DBMS?
Ans. Common aggregation functions in DBMS include SUM, AVG, MIN, MAX, and COUNT.
Q2. How is aggregation used in SQL queries?
Ans. Aggregation is used in SQL queries to provide summary statistics such as total sales of a product, the average salary of employees in a department, or the maximum temperature recorded in a region.
Q3. What is a group by clause in SQL?
Ans. The GROUP BY clause in SQL is used to group rows based on a column or set of columns. Aggregation functions can then be applied to each group to provide summary statistics.
Q4. What is the difference between aggregation and selection in DBMS?
Ans. Aggregation in DBMS involves computing summary statistics on a set of data, while selection involves filtering the data to retrieve a subset of rows that meet certain criteria.
Q5. What is the importance of aggregation in data analysis?
Ans. Aggregation is important in data analysis because it allows for efficient computation of summary statistics on large datasets. This is useful for gaining insights into patterns and trends in the data.
Q6. What are some common aggregation functions in DBMS?
Ans. Common aggregation functions in DBMS include SUM, AVG, MIN, MAX, and COUNT.
Q7. How is aggregation used in SQL queries?
Ans. Aggregation is used in SQL queries to provide summary statistics such as total sales of a product, the average salary of employees in a department, or the maximum temperature recorded in a region.
Q8. What is a group by clause in SQL?
Ans. The GROUP BY clause in SQL is used to group rows based on a column or set of columns. Aggregation functions can then be applied to each group to provide summary statistics.
Q9. What is the difference between aggregation and selection in DBMS?
Ans. Aggregation in DBMS involves computing summary statistics on a set of data, while selection involves filtering the data to retrieve a subset of rows that meet certain criteria.