Aggregate functions in SQL Server

Kiran Kumar

1y629General

What are aggregate functions in SQL Server and its Types

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Harshit Pandey1y ago
Accepted answer
In SQL Server, aggregate functions are built-in functions that perform a calculation on a set of values and return a single summarized result. They are commonly used with the GROUP BY clause to group rows that share the same values into summary rows.

Common Types of Aggregate Functions:
1. SUM()
  
  Calculates the total sum of a numeric column.
  
  Example: SELECT SUM(Salary) FROM Employees;
2. AVG()
  
  Returns the average value of a numeric column.
  
  Example: SELECT AVG(Age) FROM Users;
3. COUNT()
  
  Returns the number of rows that match a specified condition.
  
  Example: SELECT COUNT(*) FROM Orders;
4. MIN()
  
  Returns the smallest value in a column.
  
  Example: SELECT MIN(Price) FROM Products;
5. MAX()
  
  Returns the largest value in a column.
  
  Example: SELECT MAX(Score) FROM Results;
6. COUNT(DISTINCT column)
  
  Returns the number of unique (non-duplicate) values.
  
  Example: SELECT COUNT(DISTINCT Department) FROM Employees;
Note: Aggregate functions ignore NULL values (except COUNT(*), which counts all rows).
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Sandhiya Priya1y ago
Aggregate functions in SQL Server are used to perform calculations on multiple values and return a single summary value. They are commonly used with GROUP BY for reporting and analysis.

Here are the most commonly used aggregate functions:

1. SUM()

Returns the total sum of a numeric column.
```
SELECT SUM(Salary) AS TotalSalary FROM Employees;
```
2. AVG()

Returns the average value.
```
SELECT AVG(Salary) AS AverageSalary FROM Employees;
```
3. COUNT()

Returns the number of rows.
```
SELECT COUNT(*) AS TotalEmployees FROM Employees;
```
4. MAX()

Returns the maximum value.
```
SELECT MAX(Salary) AS HighestSalary FROM Employees;
```
5. MIN()

Returns the minimum value.
```
SELECT MIN(Salary) AS LowestSalary FROM Employees;
```
Example with GROUP BY:
```
SELECT Department, AVG(Salary) AS AvgSalary
FROM Employees
GROUP BY Department;
```
This shows the average salary per department.
0
Cynthia Sathuragiri1y ago
Aggregate functions are used to calculate a single value from a group of values in a table, like total, average, minimum, or maximum.
1. COUNT() – Counts how many rows or values are there.
2. SUM() – Adds up all the numbers in a column.
3. AVG() – Finds the average of numbers.
4. MIN() – Finds the smallest value.
5. MAX() – Finds the largest value.
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