he SQL GROUP BY syntax
The general syntax is:

1. SELECT column-names
2. FROM table-name
3. WHERE condition
4. GROUP BY column-names

The general syntax with ORDER BY is:

1. SELECT column-names
2. FROM table-name
3. WHERE condition
4. GROUP BY column-names
5. ORDER BY column-names

SQL GROUP BY Examples

Problem: List the number of customers in each country
 

1. SELECT COUNT(Id), Country
2. FROM Customer
3. GROUP BY Country

Results: 21 records.
 

Count	Country
3	Argentina
2	Austria
2	Belgium
9	Brazil
3	Canada

Problem: List the number of customers in each country sorted high to low
 

1. SELECT COUNT(Id), Country
2. FROM Customer
3. GROUP BY Country
4. ORDER BY COUNT(Id) DESC

Results: 21 records.
 

Count	Country
13	USA
11	France
11	Germany
9	Brazil
7	UK

Problem: List the total amount ordered for each customer
 

1. SELECT SUM(O.TotalPrice), C.FirstName, C.LastName
2. FROM [Order] O JOIN Customer C
3. ON O.CustomerId = C.Id
4. GROUP BY C.FirstName, C.LastName
5. ORDER BY SUM(O.TotalPrice) DESC

This query uses a JOIN with Customer to obtain customer names

Results: 89 records.
 

Sum	FirstName	LastName
117483.39	Horst	Kloss
115673.39	Jose	Pavarotti
113236.68	Roland	Mendel
57317.39	Patricia	McKenna
52245.90	Paula	Wilson
34101.15	Mario	Pontes
32555.55	Maria	Larsson