SQL Server 2012 Build-In Functions

Function	AVG
Description	Calculates the average of the Values in a Group.
Syntax	AVG (<>)
Optional	ALL  OR DISTINCT keyword can be used before the <> to get Average based on all values or Distinct values
Example	Select AVG(Math_Marks) From StudentMarks Group By Sections

Function	COUNT
Description	Gives no of items in a group
Syntax	COUNT (<>/ *)
Optional	ALL  OR DISTINCT keyword can be used before the <> to get count of all values or Distinct values
Example	Select Count(Student) From StudentMarks Group By Sections