I connected lap and desktop via crossover and assign ipv4 address .
after that I ping and got reply success
after I open mysql connection and type,
host-ip of pc,username,password and access to specified ip address's pc DB success.
Like wise I follow those steps for lan network which centralised by switch. It ping success each whatever I want pc from all computers
before ping I run ipconfig command to got ip addresses. then I see ipv6 and ipv4 address.
then my problem,
same way I used lap and desktop, I open mysql connection window and put server machine ipv4 address and trying to connect. it connected but won't show db. but db was on that pc.
after all I run **arp -a **command and gathered all ip address of this lan network. then I put all ip address at host part of connection one by one. but there is no db from all pc's. when I checked manually on sever there was db.
for this reason I enter some ip addresses which are not assign on that lan. (ip entered at host part of connection ) then there also it connect without any problems.

I'm not sure what the question in all of that was, but It sounds like you had an IP conflict, and figured it out. If you are still having a problem, maybe you could give more specific details about your adaptersetting, and what our hope to accomplish.