Aggregate Function is a database function used in Structured Query Language (SQL) to perform calculations on sets of data. Aggregate functions process data records and return a single value. Typically, aggregate functions are used in combination with a Group By clause of a SELECT statement. Examples of Aggregate functions include SUM, AVG, MIN, MAX, COUNT, VARIANCE, and STANDARD DEVIATION.
The syntax used for most aggregate functions is as follows:
SELECT [aggregate_function(column_name)]
FROM table
WHERE [condition];
For example, the following statement retrieves the average purchase price of a product from a table:
SELECT AVG(PurchasePrice)
FROM ProductsTable
WHERE Type = ‘Computer’;
In this instance, the aggregate function is used to calculate the average ‘PurchasePrice’ from a table, yielding a single result.
Aggregate functions are useful in situations where you want to summarize and analyze data from a large amount of records. They can be used in conjunction with other SQL commands, such as the GROUP BY clause, to create more powerful queries.
In addition, aggregate functions are efficient in that they provide a quick and easy way to retrieve a single result from a large set of data. By using aggregate functions, you can often save resources and time over querying for each row individually.
Aggregate functions provide a powerful tool for SQL developers, enabling complex calculations to be completed in a single command. As such, they are a key component for any database programmer.
