What is the difference between HAVING and WHERE in SQL?

HAVING: is used to check conditions after the aggregation takes place.
WHERE: is used to check conditions before the aggregation takes place.

This code:

select City, CNT=Count(1)
From Address
Where State = 'MA'
Group By City

Gives you a table of all cities in MA and the number of addresses in each city.

This code:

select City, CNT=Count(1)
From Address
Where State = 'MA'
Group By City
Having Count(1)>5

Gives you a table of cities in MA with more than 5 addresses and the number of addresses in each city.

HAVING specifies a search condition for a group or an aggregate function used in SELECT statement.

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