SQL Having Keyword

SQL HAVING clause is similar to the WHERE clause; they are both used to filter rows in a table based on conditions.
However, the HAVING clause was included in SQL to filter grouped rows instead of single rows.
These rows are grouped together by the GROUP BY clause, so, the HAVING clause must always be followed by the GROUP BY clause.
It can be used with aggregate functions, whereas the WHERE clause cannot.

SELECT column1, column2, aggregate_function(column)
FROM table_name
GROUP BY column1, column2
HAVING condition;

SELECT NAME, SUM(SALARY) as total_salary
FROM CUSTOMERS
GROUP BY NAME
HAVING SUM(SALARY) < 4540
ORDER BY NAME

SELECT AGE
FROM CUSTOMERS
GROUP BY age
HAVING COUNT(age) >= 3

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