You can reference query string parameters in Visualforce markup by using the $CurrentPage global variable. Using $CurrentPage, you can access the query string parameters for the page by specifying the parameters attribute, after which you can access each individual parameter:
$CurrentPage.parameters.parameter_name
For example, suppose you want to add detail information about a specific contact to an Account page. The account record ID is specified by the default id query string parameter, and the contact record ID is specified by the query string parameter named cid:
<apex:page standardController="Account"> <apex:pageBlock title="Hello {!$User.FirstName}!"> You are displaying values from the {!account.name} account and a separate contact that is specified by a query string parameter. </apex:pageBlock> <apex:pageBlock title="Contacts"> <apex:dataTable value="{!account.Contacts}" var="contact" cellPadding="4" border="1"> <apex:column> <apex:facet name="header">Name</apex:facet> {!contact.Name} </apex:column> <apex:column> <apex:facet name="header">Phone</apex:facet> {!contact.Phone} </apex:column> </apex:dataTable> </apex:pageBlock> <apex:detail subject="{!$CurrentPage.parameters.cid}" relatedList="false" title="false"/> </apex:page>
https://Salesforce_instance/apex/MyFirstPage?id=001D000000IRt53&cid=003D000000Q0bIE