def METHOD_NAME():
    '''
    Downgrade the database to the previous revision
    '''
    schema = context.get_context().version_table_schema + '.' if context.get_context().version_table_schema else ''
    if context.get_context().dialect.name in ['oracle']:
        try_drop_constraint('IDENTITIES_TYPE_CHK', 'identities')
        create_check_constraint(constraint_name='IDENTITIES_TYPE_CHK',
                                table_name='identities',
                                condition="identity_type in ('X509', 'GSS', 'USERPASS', 'SSH')")
        try_drop_constraint('ACCOUNT_MAP_ID_TYPE_CHK', 'account_map')
        create_check_constraint(constraint_name='ACCOUNT_MAP_ID_TYPE_CHK',
                                table_name='account_map',
                                condition="identity_type in ('X509', 'GSS', 'USERPASS', 'SSH')")
    elif context.get_context().dialect.name == 'mysql':
        execute('ALTER TABLE ' + schema + 'identities DROP CHECK IDENTITIES_TYPE_CHK')  # pylint: disable=no-member
        create_check_constraint(constraint_name='IDENTITIES_TYPE_CHK',
                                table_name='identities',
                                condition="identity_type in ('X509', 'GSS', 'USERPASS', 'SSH')")
        execute('ALTER TABLE ' + schema + 'account_map DROP CHECK ACCOUNT_MAP_ID_TYPE_CHK')  # pylint: disable=no-member
        create_check_constraint(constraint_name='ACCOUNT_MAP_ID_TYPE_CHK',
                                table_name='account_map',
                                condition="identity_type in ('X509', 'GSS', 'USERPASS', 'SSH')")
    elif context.get_context().dialect.name == 'postgresql':
        drop_constraint('IDENTITIES_TYPE_CHK', 'identities', type_='check')
        create_check_constraint(constraint_name='IDENTITIES_TYPE_CHK',
                                table_name='identities',
                                condition="identity_type in ('X509', 'GSS', 'USERPASS', 'SSH')")
        drop_constraint('ACCOUNT_MAP_ID_TYPE_CHK', 'account_map', type_='check')
        create_check_constraint(constraint_name='ACCOUNT_MAP_ID_TYPE_CHK',
                                table_name='account_map',
                                condition="identity_type in ('X509', 'GSS', 'USERPASS', 'SSH')")
        # drop_constraint('ACCOUNT_MAP_ID_TYPE_FK', 'account_map', type_='foreignkey')
        # create_foreign_key('ACCOUNT_MAP_ID_TYPE_FK', 'account_map', 'identities', ['identity', 'identity_type'], ['identity', 'identity_type'])