struct ConvDict : Convert
{
	private:
	const SqlId TBL;
	const SqlId ID;
	const SqlId NAME;
	const int   CLEARTIME;
	
	public:
	ConvDict(SqlId tbl ,SqlId id, SqlId name,int clearTime)
	: TBL(tbl)
	, ID(id)
	, NAME(name)
	, CLEARTIME(clearTime)
	{
		
	}
	
	virtual Value Format(const Value& q) const
	{
		if(q.IsNull()) return Null;
		static VectorMap<int, String> dict;
		static Time lastcleartime;
		if(GetSysTime()-lastcleartime > CLEARTIME)
		{
			dict.Clear();
			lastcleartime=GetSysTime();
		}
		
		int f = dict.Find(int(q));
		if(f >= 0)
		{
			return dict[f];
		} else {
			Sql sql;
			sql * Select(NAME).From(TBL).Where(ID == q);
			String s;
			if(sql.Fetch()) {
				int sid = int(q);
				s = sql[NAME];
				dict.Add(sid, s);
			} else {
				s = "";
			}
			return s;
		}
	}
};