SQL how to count all rows up to a max value

I am having trou开发者_运维百科ble counting the number of rows until it reaches a certain PK.

My PK is called id and I want to count all rows until i reach a specified id

I have tried using this query but it doesn't work probably becuase I am using a MySQL table

select max(count(*)) from news where id=18 group by id

I get this error

Invalid use of group function

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select count(*) from news where id<=18 

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I would use the following:

select count(id) from news where id <= 18

This will be more efficient as you are only returning one column in a row as opposed to all of them.