MySQL中的最后一个ID错误

I'm searching a query to find the last ID in a table.

I already have tried these two query's

$querycustomerid="SELECT IDCustomer FROM tblCustomer ORDER BY IDCustomer DESC LIMIT 1";
$newid = mysql_query($querycustomertid) or die ("Error in : $querycustomerid. ".mysql_error()) + 1;

$querycustomerid="SELECT MAX(IDCustomer) FROM tblCustomer";
$newid = mysql_query($querycustomerid) or die ("Error in : $querycustomerid. ".mysql_error()) + 1;

but when i echo $newid in php i get back Resource id #3

mysql_query() returns a MySQL resource. To display the contents of the resource, you can fetch the the result and display it like this:

// For the first query:
$row = mysql_fetch_row( $newid );
echo $row[0]; // To display the first column of the result set.

Besides you're using deprecated mysql_* functions, the query result of mysql_query() function is not a number, string, array etc. You must fetch this query result for example using mysql_fetch_row() function.

Instead this deprecated library consider using mysqli extension or the PDO.