Why can i sort an inline SELECT value but not use it in a WHERE clause?

I have this small SQL query.

SELECT a.`id` , a.`title` , a.`date` , 
(
    SELECT MAX( grade )
    FROM tests
    WHERE userid = 41
    AND presid = a.`id`
) AS grade
FROM `presentations` a
WHERE a.`visible` = 1
AND `grade` >= 5
ORDER BY `grade` DESC

This gives me the error

1054 - Unknown column 'grade' in 'where clause'

But if i remove the 2nd last line, it works fine. I have tried to do AND a.grade and even give the tests table a name and append that name to grade but still no luck.

How can I use this inline query in a WHERE clause?

I have found that this works, but is it the only way?

SELECT a.`id` , a.`title` , a.`date` , 
(
    SELECT MAX( grade )
    FROM tests
    WHERE userid = 41
    AND presid = a.`id`
) AS grade
FROM `presentations` a
WHERE a.`visible` = 1
AND (
    SELECT MAX( grade )
    FROM tests
    WHERE userid = 41
    AND presid = a.`id`
) >= 5
ORDER BY `grade` DESC

From stackoverflow

• SELECT  a.`id` , a.`title` , a.`date` , 
          (
          SELECT  MAX( grade )
          FROM    tests
          WHERE   userid = 41
                  AND presid = a.`id`
         ) AS grade
  FROM    `presentations` a
  WHERE   a.`visible` = 1
  HAVING  `grade` >= 5
  ORDER BY
          `grade` DESC
  

• Sql statements are somewhat evaluated in the following order:

  • FROM
  • WHERE
  • SELECT
  • GROUP
  • HAVING
  • ORDER

  So things you define in the SELECT-clause are not available in the WHERE-clause. You would need to put that constraint into a HAVING-clause:

  SELECT a.`id` , a.`title` , a.`date` , 
  (
      SELECT MAX( grade )
      FROM tests
      WHERE userid = 41
      AND presid = a.`id`
  ) AS grade
  FROM `presentations` a
  WHERE a.`visible` = 1
  HAVING `grade` >= 5
  ORDER BY `grade` DESC
  

  Ólafur Waage : There we go :) Thanks