Wrong datetime formating when building the query about superset HOT 16 CLOSED

            # UGLY: I guess correct way is to delegate on SQLAlchemy dialect
            # UPDATE: Datetime depends on each dialect and I haven't found an easy way to manage
            #         Maybe we can allow user to define its custome format at Database definition
            def get_dtformat(type):
                if type == 'SMALLDATETIME' or type == 'DATETIME':
                    return '%Y-%m-%d %H:%M:%S'
                if type == 'DATE':
                    return '%Y-%m-%d'
                if type == 'TIME':
                    return '%H:%M:%S'
                return '%Y-%m-%d %H:%M:%S.%f'

            tf = get_dtformat(cols[granularity].type or 'DATE')

-- Using default and 126 format for Datetime2
SELECT CONVERT(DATETIME2, '2015-08-10 11:58:47.123456', 126) as MSSQLDateTime2
-- Using default[:-3] and 121 format for Datetime 
SELECT CONVERT(DATETIME, '2015-08-10 11:58:47.123', 121) as MSSQLDateTime2

def dttm_sql_literal(self, dttm, type):
        """Convert datetime object to string

        If database_expression is empty, the internal dttm
        will be parsed as the string with the pattern that
        the user inputted (python_date_format)
        If database_expression is not empty, the internal dttm
        will be parsed as the sql sentence for the database to convert
        """
        tf = self.python_date_format or '%Y-%m-%d %H:%M:%S.%f'
        if self.database_expression:
            return self.database_expression.format(dttm.strftime('%Y-%m-%d %H:%M:%S'))
        elif tf == 'epoch_s':
            return str((dttm - datetime(1970, 1, 1)).total_seconds())
        elif tf == 'epoch_ms':
            return str((dttm - datetime(1970, 1, 1)).total_seconds() * 1000.0)
        else:
            default = "'{}'".format(dttm.strftime(tf))
            iso = dttm.isoformat()
            d = {
                'mssql': "CONVERT({}, '{}', {})".
                            format("DATETIME2" if type.lower() == "datetime2" else "DATETIME",
                            default if type.lower() == "datetime2" else default[:- 3],
                            126 if type.lower() == "datetime2" else 121),  # untested
                'mysql': default,
                'oracle':
                    """TO_TIMESTAMP('{}', 'YYYY-MM-DD"T"HH24:MI:SS.ff6')""".format(iso),
                'presto': default,
                'sqlite': default,
            }
            for k, v in d.items():
                if self.table.database.sqlalchemy_uri.startswith(k):
                    return v
            return default

uri = self.table.database.sqlachemy_uri
if uri.startswith('oracle'):
    iso = dttm.isoformat()
   return """TO_TIMESTAMP('{}', 'YYYY-MM-DD"T"HH24:MI:SS.ff6')""".format(iso)
elif uri.startswith('mssql'):
    field_type = type.upper()
    if field_type == 'DATETIME':
        return default[:-3]
    return default
else:
    return default