- factored out the logic used by Join to create its join condition

- With declarative, joined table inheritance mappers use a slightly relaxed
function to create the "inherit condition" to the parent
table, so that other foreign keys to not-yet-declared
Table objects don't trigger an error.

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/sqlalchemy/exceptions.py b/lib/sqlalchemy/exceptions.py
index a21a06b49..747a519f6 100644
--- a/lib/sqlalchemy/exceptions.py
+++ b/lib/sqlalchemy/exceptions.py
@@ -64,7 +64,9 @@ class AssertionError(SQLAlchemyError):
 
 class NoSuchColumnError(KeyError, SQLAlchemyError):
     """Raised by ``RowProxy`` when a nonexistent column is requested from a row."""
-
+    
+class NoSuchTableError(InvalidRequestError):
+    """Raised by ``ForeignKey`` when the referred ``Table`` cannot be located."""
 
 class DisconnectionError(SQLAlchemyError):
     """Raised within ``Pool`` when a disconnect is detected on a raw DB-API connection.