In the LAN can know how many computers installed MySQL via software or command line

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There are many network discovery tools out there that you can use. My favourite one is nmap. For example to list all computers with MySQL running (TCP port 3306 open) in one subnet:

nmap -sT -p3306 --open 10.1.0.0/24

Of course you will not see hosts that are firewalled.

I using OS MicroSoft WindowsXP, Could you told me detail ?

Have you visited the nmap website? There is also version for Windows. You can also install zenmap - graphical interface which may be easier for you. [url]http://nmap.org/download.html[/url]

I see the website [url]http://nmap.org/download.html[/url] and download nmap-6.40-setup.exe to install the machine, I tried to run Nmap software - Zenmap GUI but does not scan any computer in the network LAN have got MySQL installed. while my network LAN with several computers installed MySQL.

So the question is if the host from you are trying to scan the network is allowed to access those computers. Are you able to connect to those MySQL servers from that host with normal mysql client? If yes, then you seems to be not using nmap correctly. Also you may try to add “-P0” paramater to nmap command if only ICMP packets are blocked.
Maybe those MySQL servers are only listening on local IP addresses? Check for bind_address in your mysql configs.

I’ve tried it but do not be