def _visit_column_change(self,table_name,col_name,delta):
if not hasattr(delta,'result_column'):
# Oracle needs the whole column definition, not just a lone name/type
raise exceptions.NotSupportedError(
"A column object is required to do this")
column = delta.result_column
# Oracle cannot drop a default once created, but it can set it to null.
# We'll do that if default=None
# http://forums.oracle.com/forums/message.jspa?messageID=1273234#1273234
dropdefault_hack = (column.default is None and 'default' in delta.keys())
# Oracle apparently doesn't like it when we say "not null" if the
# column's already not null. Fudge it, so we don't need a new function
notnull_hack = ((not column.nullable) and ('nullable' not in delta.keys()))
# We need to specify NULL if we're removing a NOT NULL constraint
null_hack = (column.nullable and ('nullable' in delta.keys()))
if dropdefault_hack:
#column.default = sqlalchemy.PassiveDefault("NULL")
column.default = sqlalchemy.PassiveDefault(sqlalchemy.func.null())
if notnull_hack:
column.nullable = True
colspec=self.get_column_specification(column,override_nullable=null_hack)
if null_hack:
colspec += ' NULL'
if notnull_hack:
column.nullable = False
if dropdefault_hack:
column.default = None
self.start_alter_table(table_name)
self.append("MODIFY ")
self.append(colspec)
def _visit_column_change(self,table_name,col_name,delta):
if not hasattr(delta,'result_column'):
# Mysql needs the whole column definition, not just a lone name/type
raise exceptions.NotSupportedError(
"A column object is required to do this")
column = delta.result_column
colspec = self.get_column_specification(column)
self.start_alter_table(table_name)
self.append("CHANGE COLUMN ")
self.append(col_name)
self.append(' ')
self.append(colspec)
def visit_index(self, param):
# If MySQL can do this, I can't find how
raise exceptions.NotSupportedError("MySQL cannot rename indexes")
def get_constraint_name(self,cons):
# Oracle constraints can't guess their name like other DBs
if not cons.name:
raise exceptions.NotSupportedError(
"Oracle constraint names must be explicitly stated")
return cons.name
def _not_supported(self, op):
raise exceptions.NotSupportedError(
"SQLite does not support "
"%s; see http://www.sqlite.org/lang_altertable.html" % op)
def visit_column(self, column):
raise exceptions.NotSupportedError(
"SQLite does not support "
"DROP COLUMN; see http://www.sqlite.org/lang_altertable.html")