For Zend Framework 2.*, creating the adapter would be:
$db = new \Zend\Db\Adapter\Adapter([
'driver' => 'Pdo_Mysql',
'host' => '127.0.0.1',
'username' => 'webuser',
'password' => 'xxxxxx',
'database' => 'test',
]);
To create select:
$sql = new \Zend\Db\Sql\Sql($db);
$select = $sql->select()
->from('posts')
->where(array('cat_id' => $catId))
->order('date_posted DESC')
->limit(5);
$statement = $sql->prepareStatementForSqlObject($select);
$results = $statement->execute();
Or, if you want to get pure SQL from the $select:
$selectSql = $sql->getSqlStringForSqlObject($select);
Docs might be helpful. It can be even simpler if TableGateway is used.