Aggregation in Database
Aggregation in a database refers to the process of combining data from multiple records or tables and grouping them together based on one or more columns. This can be done using SQL aggregate functions such as SUM, COUNT, AVG, MIN, and MAX. Aggregation is often used to calculate statistics or to summarize data in a more meaningful way. Examples of aggregations include calculating the total number of sales for a specific product, the average salary of employees in a department, or the maximum temperature recorded in a given month.
Examples of Data Aggregation
Here are a few examples of data aggregation:
- Counting the number of customers in a database:
SELECT COUNT(*) FROM customers;
- Summing up the total sales for a particular product:
SELECT SUM(sales) FROM orders WHERE product_name = 'Widget';
- Calculating the average salary of employees in a department:
SELECT AVG(salary) FROM employees WHERE department = 'Marketing';
- Finding the minimum and maximum prices of products in a category:
SELECT MIN(price), MAX(price) FROM products WHERE category = 'Electronics';
- Grouping the sales data by year and calculating the total sales per year:
SELECT YEAR(sale_date), SUM(sales) FROM sales GROUP BY YEAR(sale_date);
- Grouping data by multiple columns, for example calculating average sales of product per region:
SELECT product_name, region, AVG(sales) FROM sales GROUP BY product_name, region;
These are just a few examples of the types of aggregations that can be performed on a database. There are many other aggregate functions and ways to group and summarize data.
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