Get avarage from results [php & mysql]

[gammele]

Hi there programmers,

 

I am trying to get the avarage score for a criterium out of the database.

The system is used to give grades to a meeting.

 

My database structure is like this:

 

#Results#

Result_id

Result_overall_percentage

 

#criteriumresult#

Criteriumresult_id

Criteriumresult_link_id (refers to result_id)

Criteriumresult_criterium_id (refers to criterium_id)

Criteriumresult_percentage

 

#criterium

Criterium_id

Criterium_tekst

For example:

 

1 - The employees are well prepared

2 - There was no interruption

 

What i would like to do, is write a query, which collects the avarage score of ID's.

 

//splittetResultIDs = multiple selections

$SelectQuery = mysql_query("
SELECT 
	*
FROM 
	criteriumresult
WHERE 
	Criteriumresult_link_id  IN(".$splittetResultIDs.") 
") or die (mysql_error());

 

I get a lot of results, but i would like to filter unique criteria, and only list them as unique items and with an avarege score.

How can i do this?

 

[fenway]

What's a Criterium? You mean criterion?

[Nodral]

You need to be slightly clearer on what you want.

 

There is an AVG function within MYSQL which will do what you want and you can still have a WHERE clause on it.

 

Eg

 

SELECT AVG(Result_overall_percentage) as Average FROM Results WHERE ........................

 

This will give you a return called  'Average' depending on the conditions you specify in the WHERE clause