Check Data Base is Up or Down

Sure... here's a good way to do it.

1. Wrap your code, first, in a <cftry>/<cfcatch> block.  This will arrange to neatly "catch" any unexpected condition ... like a database server that has gone down, causing your queries to time-out.
2. Within that, use a <cftransaction> block to make all of your updates (if any) atomic.  ColdFusion will neatly take care of committing the transaction if the end of the block is reached normally, and of rolling-back the transaction on failure.
3. Now, use the timeout= parameter on your <cfquery> and other statements, as appropriate for each one of them.  If a timeout occurs, an exception will be thrown and this will be taken care of by the two tags mentioned previously.  If some other type of failure is detected directly, such as "failure to connect with database server," it also will throw an exception (albeit of a different type) in the same way.
   

What's nice about this strategy is that, not only is it very rugged and reliable, but it is also very efficient.  "99.9% of the time, a timeout does not happen," but when and if it does, you can very-reliably handle it ... as the "exception to the rule" that it properly is.  You should apply this strategy in all of your code.

As far as I know you can't

You can check to see if the database is responding by trying a query

<cftry>

     <cfquery name="something" datasource="mydsn">

          select something trivial from something else trivial

     </cfquery>

     <cfcatch type="database">DB is not responding</cfcatch>

</cftry>

otherwise to see if the DB is "up" or "down" you need server access, cause it could always be up but not ersponding...

-sean