Lots of new __doc__ strings and other odds and ends

for new pydoc module in Python 2.1.

Exceptions have been moved into _mysql_const/exc.py.
Mostly this is for documentation purposes. Mostly.

mysql/_mysql_const/exc.py

@@ -0,0 +1,59 @@
+"""_mysql_const.exc: Exception classes for _mysql and MySQLdb.
+
+These classes are dictated by the DB API v2.0:
+
+    http://www.python.org/topics/database/DatabaseAPI-2.0.html
+"""
+
+from exceptions import Exception, StandardError
+
+class MySQLError(StandardError):
+    """Exception related to operation with MySQL."""
+
+class Warning(MySQLError):
+    """Exception raised for important warnings like data truncations
+    while inserting, etc."""
+    
+class Error(MySQLError):
+    """Exception that is the base class of all other error exceptions
+    (not Warning)."""
+    
+class InterfaceError(Error):
+    """Exception raised for errors that are related to the database
+    interface rather than the database itself."""
+
+class DatabaseError(Error):
+    """Exception raised for errors that are related to the database."""
+
+class DataError(DatabaseError):
+    """Exception raised for errors that are due to problems with the
+    processed data like division by zero, numeric value out of range, etc."""
+
+class OperationalError(DatabaseError):
+    """Exception raised for errors that are related to the database's
+    operation and not necessarily under the control of the programmer,
+    e.g. an unexpected disconnect occurs, the data source name is not
+    found, a transaction could not be processed, a memory allocation error
+    occurred during processing, etc."""
+
+class IntegrityError(DatabaseError):
+    """Exception raised when the relational integrity of the database
+    is affected, e.g. a foreign key check fails, duplicate key, etc."""
+
+class InternalError(DatabaseError):
+    """Exception raised when the database encounters an internal error,
+    e.g. the cursor is not valid anymore, the transaction is out of sync,
+    etc."""
+
+class ProgrammingError(DatabaseError):
+    """Exception raised for programming errors, e.g. table not found or
+    already exists, syntax error in the SQL statement, wrong number of
+    parameters specified, etc."""
+
+class NotSupportedError(DatabaseError):
+    """Exception raised in case a method or database API was used which
+    is not supported by the database, e.g. requesting a .rollback() on a
+    connection that does not support transaction or has transactions turned
+    off."""
+
+del Exception, StandardError