Where Vs Having

You use WHERE for filtering rows before applying any grouping or aggregation. The code snippet below illustrates the use of WHERE. It filters the Users table for rows where the Age is greater than 18.

SELECT * FROM Users
WHERE Age > 18;

The result of the query is similar to the table below.

On the other hand, you use HAVING to filter groups after performing grouping and aggregation. You apply it to the result of aggregate functions, and it is mostly used with the GROUP BY clause.

SELECT FirstName, Age FROM Users
GROUP BY FirstName, Age
HAVING Age > 30;

The code above selects the FirstName and Age columns, then groups by the FirstName and Age, and finally gets entries with age greater than 30. The result of the query looks like this: