Difference between HAVING and WHERE

Question

I have this table,

CREATE TABLE Person 
    (
     id int auto_increment primary key, 
     name varchar(20), 
     Age varchar(30)
    );

INSERT INTO Person
(name, Age)
VALUES
('Ganesan', '23'),
('Prasanna', '30'),
('Karthikeyan', '27'),
('RParthiban', '33');

And this query:

select Name, Age from Person HAVING Age > 30;

select Name, Age from Person WHERE Age > 30;

Both queries produces the same output:

NAME    AGE
RParthiban  33

Why ? Whats the difference or significance between using Having and Where ?

I am sure that there must be any. Any examples for each ?

Thanks.

@SonerGönül Why read the documentation when you can type out a question on Stack Overflow? — ta.speot.is, Nov 13 '13 at 11:17
@ta.speot.is Which it takes probably 30 seconds to search it `:)` — Soner Gönül, Nov 13 '13 at 11:18

score 2 · Answer 1 · answered Nov 13 '13 at 11:14

A HAVING clause is equivalent to a WHERE clause for a group or aggregate.

http://technet.microsoft.com/en-us/library/ms180199.aspx

The syntax is SELECT ... FROM ... GROUP BY ... HAVING ... ORDER BY

e.g.

SELECT ID, SUM(whatever) AS [Total]
FROM table
GROUP BY ID
HAVING SUM(whatever) > 100000.00
ORDER BY ID

score 1 · Accepted Answer · answered Nov 13 '13 at 11:15

If you search about this question, you will get the answer. Here is one of them

HAVING can be used only with the SELECT statement. HAVING is typically used in a GROUP BY clause. When GROUP BY is not used, HAVING behaves like a WHERE clause.

Reference

score 1 · Answer 3 · answered Nov 13 '13 at 11:16

1

WHERE is for filtering query results based on condition.

HAVING is for applying a filter on results of an aggregate function. In absence of aggregate function it functions same as WHERE.

answered Nov 13 '13 at 11:16

naveen goyal

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Difference between HAVING and WHERE

3 Answers3