SQL Aggregate Functions

The SQL Aggregate Functions are functions that provide mathematical operations. If you need to add, count or perform basic statistics, these functions will be of great help.  

The functions include:

• count() - counts a number of rows
• sum() - compute sum
• avg() - compute average
• min() - compute minimum
• max() - compute maximum

SQL Aggregate Functions are used as follows. If a grouping of values is needed also include the GROUP BY clause.

Use a column name or expression as the parameter to the Aggregate Function. The parameter, '*', represents all rows.

SQL Aggregate Functions Syntax

SQL Aggregate Functions Example

The following example Aggregate Functions are applied to the employee_count of the branch table. The region_nbr is the level of grouping.

Here are the contents of the table:

Table: BRANCH

branch_nbr	branch_name	region_nbr	employee_count
108	New York	100	10
110	Boston	100	6
212	Chicago	200	5
404	San Diego	400	6
415	San Jose	400	3

This SQL Statement with aggregate functions is executed:

Here is the result.

region_nbr	count (branch_nbr)	sum (employee_count)	min (employee_count)	max (employee_count)	avg (employee_count)
100	2	16	6	10	8
200	1	5	5	5	5
400	2	9	3	6	4