How to have a sum() with a where clause - php

Question

I currently have:
// connect for other mins
$sql = "SELECT sum(mins) FROM completed_activity WHERE member_id = '$_SESSION[SESS_MEMBER_ID]' AND exercise != 'Personal Training' AND date >= '$mon'";
But, when the date is not within the where clause, nothing is shown. I'm not even getting my 'else' statement.
Any ideas?
MAYBE SOLVED
I may have got the correct way of doing it with:
$sql = "SELECT sum(CASE WHEN member_id = '$_SESSION[SESS_MEMBER_ID]' AND exercise != 'Personal Training' AND date >= '$mon' THEN mins ELSE 0 END) AS mins FROM completed_activity";
Can anyone confirm if this looks right?

Answer 1

When using SUM, there are at least one result returned. The result of SUM may be 0 or more.
That's why your code is not working correctly.
Try the following code:
// connect for other mins
$sql = "SELECT sum(mins) AS mins_sum FROM completed_activity WHERE member_id = '$_SESSION[SESS_MEMBER_ID]' AND exercise != 'Personal Training' AND date >= '$mon'";
$result = $conn->query($sql);
while($row = $result->fetch_assoc()) {
$mins = $row["mins_sum"];
if ($mins > 0) {
echo "yes";
} else {
echo "no";
}
}

Answer 2

I dont know php code, But When No condition matched sql query will return 0.
Means There will be atleast 1 record. So your if condition will always true.
Improve condition to check for value like
if ($result['sum'] > 0) { //Check for syntax
while($row = $result->fetch_assoc()) {
$mins = $row["mins"];
echo "yes";
}
} else {
$mins = 0;
echo "no";
}