def get_sql(self, with_default_expression=True):
if with_default_expression:<EOL><INDENT>if self.alias:<EOL><INDENT>return '<STR_LIT>' % (self.db_type, self.alias)<EOL><DEDENT>elif self.materialized:<EOL><INDENT>return '<STR_LIT>' % (self.db_type, self.materialized)<EOL><DEDENT>else:<EOL><INDENT>default = self.to_db_string(self.default)<EOL>return '<STR_LIT>' % (self.db_type, default)<EOL><DEDENT><DEDENT>else:<EOL><INDENT>return self.db_type<EOL><DEDENT>
Returns an SQL expression describing the field (e.g. for CREATE TABLE).
:param with_default_expression: If True, adds default value to sql.
    It doesn't affect fields with alias and materialized values.