thank you both for your anwsers again, i made my tries on MySQL with unamed (didn't try with Add params), and moved to named params again.
It was in a attempt to send to MySQL a lot of tag words at once but with a secure way (against sql injections,where FCL hides the mysql_real_escape_string() into a private EscapeString()). Finally i made it but as i see not at once (due to many parameters, this seems that it needs a stored procedure for that).
one query is something like that
qry_.SQL.Text:=Format('insert ignore into tags (tag) select temp.tag from (%s) temp',[s]);
for i:=0 to value_list.count-1 do
qry_.ParamByName(IntToStr(i)).AsString:=value_list.strings[i];
which seems to work, in my tests i managed to send 3000 tags with one query (takes some sec, due to roundtrips for 3000 params), which seems to cover my needs for the time.