How to: using SQL the HAVING clause

HAVING clause
The HAVING clause allows you to specify conditions on the rows for each group - in other words, which rows should be selected will be based on the conditions you specify. The HAVING clause should follow the GROUP BY clause if you are going to use it.
HAVING clause syntax:

SELECT column1, 
SUM(column2)
FROM "list-of-tables"
GROUP BY "column-list"
HAVING "condition";

HAVING can best be described by example. Let's say you
have an employee table containing the employee's name, department,
salary, and age. If you would like to select the average salary for
each employee in each department, you could enter:

SELECT dept, avg(salary)
FROM employee
GROUP BY dept;

But, let's say that you want to ONLY calculate & display the average
if their salary is over 20000:

SELECT dept, avg(salary)
FROM employee
GROUP BY dept
HAVING avg(salary) > 20000;

NOTE: How to: using SQL the HAVING clause

back to the top