[Question] About 2 table in one database

[Yao Feng]

  I think the manual of mysql is few to satisfy a newbie in sql.I have 
one question in this:
  One DATABASE data;
  include two TABLE log and ip;
  What I want to do is:
  update (or substitute) the TABLE log 's COLUMN url with TABLE ip 's 
COLUMN newip IF some condition happens(such as both TABLE 's COLUMN flag 
are same).

  Any advices to do it? It confused me for a few days.