>Can we do MS SQL server be active part
>Some db events can be unhomogenious
>For example, insert to some table can be very active some time (100 per minute) or
>It can be full silence for long time
>It seems to write constant query at client due to some timer is not good in this case
>Inside Enterprise manager we can see active connections ( in Oracle too)
>Is it possible to server to send some messages to working clients and say-
>Query this table, it changed a lot.
>If possible, how to catch this message
>Sure e-mail is one way, what else
>This is not fake task My friend do program to the plant and some data are gathered from
>conveer.
>The products ( cars parts, electronics does not matter)
> some time gous out each minute or mashine can be stoped for hours

It should be possible.
Use Insert, Update and delete trigers to catch events when data changes.
For notifing the client for that events you can use e-mail as you have said (in local network with email server it should be fast) or push subscriber database.
Note that the second option has no difference with the situation for periodically looking for changes in the server table.

HTH