I used pfsense 2.01, How to i can use pfsense log in database?
Or can i save my client log for long time?
Generally speaking if you need long term logging you should use a separate syslog server.
Which logs do you need? Which install type are you running?
I need logs for squid proxy clients when squid joined to LDAP…
Then yes you should use a syslog server.
can i install postgresql or Mysql on pfsense for save my logs?
You may be able to (it would no doubt require a lot of command line hackery) but I definitely recommend you don't.
You should install a syslog server on another machine and configure pfSense to send it's logs there.
If you really want to use only one machine there is a syslog-ng package for pfSense so you can store long term logs locally if you are running a full install. I've never tried that though.