Thanks @ashleyherbert for this. it worked for me but the problem is with this the submit button has stopped working means with this code i have to mark "search on change = true", with search on change = false the above code doesn't work.
So is there any way to to make this code work without "search on change = true". It would be great help.. below is the code
<label>Connection Id (Only for PF App)</label>
<choice value="All">All</choice>
<change>
<condition>
<eval token="connection">case(mvcount('connection')=0,"All",mvcount('connection')>1 AND mvfind('connection',"All")>0,"All",mvcount('connection')>1 AND mvfind('connection',"All")=0,mvfilter('connection'!="All"),1==1,'connection')</eval>
<eval token="connection">if(mvfind('connection',"All")=0,"connectionid=*",connectionid $connection$)</eval>
</condition>
</change>
<fieldForLabel>connectionid</fieldForLabel>
<fieldForValue>connectionid</fieldForValue>
... View more