Question

I have this table :

I would like to delete same rows. For example first five rows are the same, my table should have only one row that includes this data : 40.792274 29.412994 2011-12-21 17:19:52.

So I used the following code :

$query = "SELECT * FROM table GROUP BY date";
$result = mysql_query($query);

while($row = mysql_fetch_array($result)){

    $date = $row['date'];
    $lat = $row['latitude'];
    $lon = $row['longitude'];
    $query = "SELECT * FROM table WHERE date='$date' AND latitude='$lat' AND longitude='$lon'";
    $re = mysql_query($query);
    $number = mysql_num_rows($re);
    $number--;

    $query = "DELETE * FROM table WHERE date='$date' AND latitude='$lat' AND longitude='$lon' LIMIT $number";

    mysql_query($query);
}

But this code doesn’t work.. What should I do ?

Edited :

I solved my question :

$query = "SELECT * FROM table GROUP BY date";
$result = mysql_query($query);

while($row = mysql_fetch_array($result)){

    $date = $row['date'];
    $lat = $row['latitude'];
    $lon = $row['longitude'];
    $query = "SELECT * FROM table WHERE date='$date' AND latitude=$lat AND    longitude=$lon";
    $re = mysql_query($query);
    $number = mysql_num_rows($re);
    $number--;

    $query = "DELETE FROM table WHERE date='$date' AND latitude=$lat AND longitude=$lon LIMIT $number";

    mysql_query($query);
}

Query lines were incorrect in my first question.

Answer 1

To remove the duplicate elements, you would use something like this:

$q = "SELECT date FROM table GROUP BY date"
$r = mysql_query($r);
$date = '';
while($row = mysql_fetch_array($r)){
    $date = $row['date'];
    $q = "SELECT date FROM mytable WHERE date='$date'";
    $re = mysql_query($q);
    $num = mysql_num_rows($re);
    $num--;
    $q = "DROP FROM mytable WHERE date='$date' LIMIT $num";
    mysql_query($q);
}

Should do the trick. More specifically, when creating your $date value, you have to provide PHP with a time to use. date() defaults to using the current time, but you can provide it with a custom time as the second argument.

I suggest you take a look at the strtotime() manual at php.net as well (To translate times in your db to timestamps that can be used with date() ).

EDIT: The Answer above has been edited to remove all duplicate entries.