Aggregate functions are applied to a group of data values from a column. : Aggregate function « Aggregate Functions « SQL Server / T-SQL Tutorial






  1. SQL Server / T-SQL Tutorial
  2. Aggregate Functions
  3. Aggregate function
Aggregate functions always return a single value. 

The Transact-SQL language supports six aggregate functions:
AVG
MAX
MIN
SUM
COUNT
COUNT_BIG

AVG (short for average) calculates the arithmetic mean of the data values contained within a column. The column must contain numeric values. 
MAX calculates the maximum, and MIN the minimum, data value of the column. 
The column can contain numeric, string, and date/time values.
SUM calculates the total of all data values in a column. 
The column must contain numeric values. 
COUNT calculates the number of (non-null) data values in a column. 
The only aggregate function not being applied to columns is COUNT(*). 
This function returns the number of rows (whether or not particular columns have null values). 
COUNT_BIG function is analogous to the COUNT function. 
The only difference is that COUNT_BIG returns a value of the BIGINT data type.








9.1.Aggregate function
9.1.1.Aggregate functions are applied to a group of data values from a column.
9.1.2.Using calculations within aggregate functions.
9.1.3.Query with aggregate function as a column
9.1.4.Aggregate function in sub query
9.1.5.Using Aliase with aggregate function