PDO取得最大价值

Question

I have been researching for the past hour with no luck, i've tried so many methods. All I want to do to is get the largest value from a certain column in a table and store it in a variable in php that I can use for whatever I want. Here's where I'm at so far:

$link = new PDO('mysql:host=****;dbname=****;charset=UTF-8','****','****');
$gid = $link->prepare("SELECT MAX(Group_ID) as maxGroup FROM Conference");
$gid->execute();
$test = $gid->fetch(PDO::OBJ);
echo $test;

At this point I don't even know if OBJ is correct, I'm just trying so many different things. Can anyone help me out, what do I need to do? I just want to get the largest value and store it in a variable.

Answer 1

You are returning an object, so you need to access the properties accordingly:

echo $test->maxGroup;

The ->fetch(PDO::OBJ); returns the results of the query and creates an object with properties based on the columns/aliases you have in your query.

Edit: If you are just trying to return the results and trying a few different ways, why not just do it in a simple way:

$test = $sth->fetch(PDO::FETCH_ASSOC);
echo $test['maxGroup'];

Answer 2

Why not directly association?

$link = new PDO('mysql:host=****;dbname=****;charset=UTF-8','****','****');
$gid = $link->prepare("SELECT MAX(Group_ID) as maxGroup FROM Conference");
$gid->execute();
$test = $gid->fetch(PDO::FETCH_ASSOC);
echo $test['maxGroup'];

Answer 3

i create a simple function for who want to use it simple but helpfull for the pdo() it's a simple function i know from my heart that you know what i mean with it

function last_inserted($column,$table){
 $dbh = pdo();
 $gid = $dbh->prepare("SELECT MAX(".$column.") as maxGroup FROM ".$table);
 $gid->execute();
 $last = $gid->fetch(PDO::FETCH_ASSOC);
 return $last['maxGroup'];
 }