My code is
function lister($a,$con){
$queryq = " SELECT * FROM note WHERE date= MAX(date) AND id='".$a."' AND admin='".$_SESSION['login_username']."' ";
$resultq = mysqli_query($con,$queryq) or die('Error: ' . mysqli_error($con));
$arrayq=mysqli_fetch_array($resultq,MYSQL_NUM); {
echo $arrayq[4];
}
}
There is an error:
Error: Invalid use of group function
What am I doing wrong?
try to split the query
$queryA = "SELECT date FROM `note` WHERE id='".$a."' AND admin='".$_SESSION['login_username']."' ORDER BY date DESC LIMIT 1";
$resultA = mysql_query($con, $queryA);
$maxDatePerUser = mysql_fetch_array($resultA);
$queryq = " SELECT * FROM note WHERE id='".$a."' AND admin='".$_SESSION['login_username']."' AND date='" . $maxDatePerUser["date"] ."'";
$resultq = mysqli_query($con,$queryq) or die('Error: ' . mysqli_error($con));
$arrayq=mysqli_fetch_array($resultq,MYSQL_NUM); {
The problem is caused by a circular reference of sorts.
SELECT * FROM note WHERE date= MAX(date) AND id='".$a."' AND admin='".$_SESSION['login_username']."' "
You're asking the function to calculate something based on that same thing - a condition of the statement is MAX(date), but it can't calculate that until it knows what it is.
The best solution is to find MAX(date) separately:
SELECT max(date) FROM note
You can add additional restrictions, if necessary, if it is the max date WHERE, ie
SELECT max(date) FROM note WHERE id='".$a."' AND admin='".$_SESSION['login_username']."' "
Once you have this, you can pop it back in the query:
SELECT * FROM note
WHERE date = (SELECT max(date)
FROM note
WHERE id = '" . $a . "'
AND admin = '" . $_SESSION['login_username'] . "')
AND id = '" . $a . "'
AND admin = '" . $_SESSION['login_username'] . "';
Hard to get the query 100% right without having the data to test on, but that should work.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.