SELECT product, SUM(quantity) AS "Total quantity"
FROM order_details
GROUP BY product;

Assume a table of employees in which each row is an employee who has a name, a department, and a salary.

SELECT department, MIN(salary) AS "Lowest salary"
FROM employees
GROUP BY department;

This would tell you which department contains the employee with the lowest salary, and what that salary is. Finding the name of the employee with the lowest salary in each department is a different problem, beyond the scope of this Example. See "groupwise max".

SELECT department, COUNT(*) AS "Man_Power"
FROM employees
GROUP BY department;

SELECT department, COUNT(*) AS "Man_Power"
FROM employees
GROUP BY department
HAVING COUNT(*) >= 10;

Using GROUP BY ... HAVING to filter aggregate records is analogous to using SELECT ... WHERE to filter individual records.

You could also say HAVING Man_Power >= 10 since HAVING understands "aliases".

Group Concat is used in MySQL to get concatenated values of expressions with more than one result per column. Meaning, there are many rows to be selected back for one column such as Name(1):Score(*)

Name	Score
Adam	A+
Adam	A-
Adam	B
Adam	C+
Bill	D-
John	A-

SELECT Name, GROUP_CONCAT(Score ORDER BY Score desc SEPERATOR ' ') AS Grades
FROM   Grade
GROUP BY Name

Results:

+------+------------+ 
| Name | Grades     | 
+------+------------+ 
| Adam | C+ B A- A+ | 
| Bill | D-         | 
| John | A-         | 
+------+------------+ 

Table ORDERS

+---------+------------+----------+-------+--------+
| orderid | customerid | customer | total | items  |
+---------+------------+----------+-------+--------+
|       1 |          1 | Bob      |  1300 |     10 |
|       2 |          3 | Fred     |   500 |      2 |
|       3 |          5 | Tess     |  2500 |      8 |
|       4 |          1 | Bob      |   300 |      6 |
|       5 |          2 | Carly    |   800 |      3 |
|       6 |          2 | Carly    |  1000 |     12 |
|       7 |          3 | Fred     |   100 |      1 |
|       8 |          5 | Tess     | 11500 |     50 |
|       9 |          4 | Jenny    |   200 |      2 |
|      10 |          1 | Bob      |   500 |     15 |
+---------+------------+----------+-------+--------+

• COUNT

Return the number of rows that satisfy a specific criteria in WHERE clause.

E.g.: Number of orders for each customer.

SELECT customer, COUNT(*) as orders
FROM orders
GROUP BY customer
ORDER BY customer

Result:

+----------+--------+
| customer | orders |
+----------+--------+
| Bob      |      3 |
| Carly    |      2 |
| Fred     |      2 |
| Jenny    |      1 |
| Tess     |      2 |
+----------+--------+

• SUM

Return the sum of the selected column.

E.g.: Sum of the total and items for each customer.

SELECT customer, SUM(total) as sum_total, SUM(items) as sum_items
FROM orders
GROUP BY customer
ORDER BY customer

Result:

+----------+-----------+-----------+
| customer | sum_total | sum_items |
+----------+-----------+-----------+
| Bob      |      2100 |        31 |
| Carly    |      1800 |        15 |
| Fred     |       600 |         3 |
| Jenny    |       200 |         2 |
| Tess     |     14000 |        58 |
+----------+-----------+-----------+

• AVG

Return the average value of a column of numeric value.

E.g.: Average order value for each customers.

SELECT customer, AVG(total) as avg_total
FROM orders
GROUP BY customer
ORDER BY customer

Result:

+----------+-----------+
| customer | avg_total |
+----------+-----------+
| Bob      |       700 |
| Carly    |       900 |
| Fred     |       300 |
| Jenny    |       200 |
| Tess     |      7000 |
+----------+-----------+

• MAX

Return the highest value of a certain column or expression.

E.g.: Highest order total for each customers.

SELECT customer, MAX(total) as max_total
FROM orders
GROUP BY customer
ORDER BY customer

Result:

+----------+-----------+
| customer | max_total |
+----------+-----------+
| Bob      |      1300 |
| Carly    |      1000 |
| Fred     |       500 |
| Jenny    |       200 |
| Tess     |     11500 |
+----------+-----------+

• MIN

Return the lowest value of a certain column or expression.

E.g.: Lowest order total for each customers.

SELECT customer, MIN(total) as min_total
FROM orders
GROUP BY customer
ORDER BY customer

Result:

+----------+-----------+
| customer | min_total |
+----------+-----------+
| Bob      |       300 |
| Carly    |       800 |
| Fred     |       100 |
| Jenny    |       200 |
| Tess     |      2500 |
+----------+-----------+