doctrine/dbal — pull request #467 by deeky666 (2013-12-27 14:43:49+00:00)
Title: [DBAL-472] Fix altering column from notnull to null in Oracle

Oracle requires an explicit `NULL` clause when altering a column from `NOT NULL` to `NULL`. Otherwise the existing notnull constraint remains unchanged.
This PR changes Oracles column declaration SQL snippet to always specify `NULL` and `NOT NULL` in `CREATE TABLE` and `ALTER TABLE` statements. This is a perfectly valid syntax and also functional tested.