Changes from Query
Additional aggregate methods
In addition to the Query aggregate methods which can still be used, the following methods will return a numeric value of an aggregate function; getAvg(), getMin(), getMax(), getSum(). 
$result = $db->table('movies')->getAvg('year');
// 1996
$result = $db->table('movies')->getMax('year');
// 2020
$result = $db->table('movies')->getMin('year');
// 1921
The getCount() method now returns an Integer representing the number of rows in the result.
$result = $db->table('movies')->getCount();
// 4803
$result = $db->table('movies')->where('title', 2001)->getCount();
// 1
The getExists() method is similar to getCount() but returns a Boolean value.
$result = $db->table('movies')->where('title', 2001)->getExists();
// true
$result = $db->table('movies')->where('title', 5001)->getExists();
// false
Data operations
The insert(), update() and delete() methods now operate on the table returning the number of rows affected by the operation. 
$affected_rows = $db->insert($items);
$affected_rows = $db->update($items);
$affected_rows = $db->delete($items);
Use the insertGetId() method to return the id of the new row.
$item->id = $db->insertGetId($item);
// using a loop to get multiple ids
foreach ($items as $item) {
    $item->id = $db->insertGetId($item);
}