MySQL doing an average calculation and output into a php variable

Question

i am not sure if i am doing this correctly, and i am kinda stucked here.

Here's what i want to do, each row in the database has 5 column, say A,B,C,D with each having an integer value out of 10 and E which is like a counter. so what i want is to get an average.

which should be something like below

(A + B + C + D)/(E * 4)

and each of these values calculated above, has to be summed up and divide by the total number of rows.

So say i have 3 entry it has to divided by 3

so what i came up with is

$myresult = mysql_query("SELECT * FROM studies WHERE classes = '$classid'");
list($mycount) = mysql_fetch_row($myresult);
$result = mysql_query("SELECT ID, sum((maths + sciences + moral + bm)/(count*4))/'$mycount' FROM studies WHERE classes = '$classid'");

am i doing this right?

if the sql is right, how am i suppose to print out the result so i can use it as a variable?

thank you

column needs alias: SELECT id, sum((maths + .........)) as 'avg' ... so you will have avg row keys in your fetched array — Ivan Yonkov
– Ivan Yonkov, Commented Sep 14, 2013 at 15:01

Vilsol · Accepted Answer · 2013-09-14 15:03:20Z

1

The query should be right, but to get the actual value is easy. You have to fetch_array the query, and the first variable would be the ID and the second would be the sum.

Example

while($row = mysql_fetch_array($query)){
echo $row[0]; // This is the ID
echo $row[1]; // This is the sum
}

answered Sep 14, 2013 at 15:03

Vilsol

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