    deferred class
    	DB_EXPRESSION

    General
    	cluster: interface

    Ancestors
    	STRING_HDL

    Queries
    	ht: HASH_TABLE [ANY, STRING_8]
    	ht_order: ARRAYED_LIST [STRING_8]
    	is_mapped (key: STRING_8): BOOLEAN
    	last_query: STRING_8
    	mapped_value (key: STRING_8): ANY

    Commands
    	clear_all
    	execute_query
    	set_map_name (n: ANY; key: STRING_8)
    	set_query (query: STRING_8)
    	unset_map_name (key: STRING_8)