doctrine/doctrine2 — comment on commit 0380d5ae580dcbefd63051028fc1ab78599fda6c
File: tests/Doctrine/Tests/ORM/Query/SelectSqlGenerationTest.php line 454
By guilhermeblanco:

IDENTITY() should only be used in SelectExpressions. I added there to illustrate support for functions.
The idea of IDENTITY() is to retrieve fk columns only of a single valued association.
Example:

```sql
SELECT IDENTITY(u.Group) FROM User u
===
SELECT c0_.group_id FROM users u
```