Updated UPGRADE.md for 2.x

UPGRADE.md

@@ -12,6 +12,15 @@
 
 ``Doctrine\DBAL\Connection::TRANSACTION_*`` were moved into ``Doctrine\DBAL\TransactionIsolationLevel`` class without the ``TRANSACTION_`` prefix. 
 
+## DEPRECATION: direct usage of the PDO APIs in the DBAL API
+
+1. When calling `Doctrine\DBAL\Driver\Statement` methods, instead of `PDO::PARAM_*` constants, `Doctrine\DBAL\ParameterType` constants should be used.
+2. When calling `Doctrine\DBAL\Driver\ResultStatement` methods, instead of `PDO::FETCH_*` constants, `Doctrine\DBAL\FetchMode` constants should be used.
+3. When configuring `Doctrine\DBAL\Portability\Connection`, instead of `PDO::CASE_*` constants, `Doctrine\DBAL\ColumnCase` constants should be used.
+4. Usage of `PDO::PARAM_INPUT_OUTPUT` in `Doctrine\DBAL\Driver\Statement::bindValue()` is deprecated.
+5. Usage of `PDO::FETCH_FUNC` in `Doctrine\DBAL\Driver\ResultStatement::fetch()` is deprecated.
+6. Calls to `\PDOStatement` methods on a `\Doctrine\DBAL\Driver\PDOStatement` instance (e.g. `fetchObject()`) are deprecated.
+
 # Upgrade to 2.6
 
 ## MINOR BC BREAK: `fetch()` and `fetchAll()` method signatures in `Doctrine\DBAL\Driver\ResultStatement`