# Getting and Setting Query String Parameters on a Single Page

Having seen examples of both getting and setting query string parameters, this example shows how the two actions can be combined on a single page to produce a more interesting result. Based on the example from Getting Query String Parameters, the following page makes the name of each contact in the list a hyperlink that controls the context of the detail component below it.

This is possible by:

- Wrapping the data table in an `<apex:form>` tag
- Turning each contact name into an `<apex:commandLink>` that sets the `cid` parameter appropriately with an `<apex:param>` tag

When used with a standard controller, command links always entirely refresh the current page with the new information added to the page—in this case, an updated `cid` that updates the contact detail component.

```markup
<apex:page standardController="Account">
    <apex:pageBlock title="Hello {!$User.FirstName}!">
        You are displaying contacts from the {!account.name} account. 
        Click a contact's name to view his or her details.
    </apex:pageBlock>
    <apex:pageBlock title="Contacts">
        <apex:form>
            <apex:dataTable value="{!account.Contacts}" var="contact" cellPadding="4" 
                               border="1">
              <apex:column>
               <apex:facet name="header">Name</apex:facet>
               <apex:commandLink>
                 {!contact.Name}
                 <apex:param name="cid" value="{!contact.id}"/>
               </apex:commandLink> 
              </apex:column>
              <apex:column>
               <apex:facet name="header">Phone</apex:facet>
               {!contact.Phone}
              </apex:column>
            </apex:dataTable>
        </apex:form>
    </apex:pageBlock>
    <apex:detail subject="{!$CurrentPage.parameters.cid}" relatedList="false" title="false"/>
</apex:page>
```

After saving this markup, refresh your browser with the `id` query string parameter but without the `cid` parameter in the URL For example,

```nolang
https://MyDomain_login_URL/apex/MyFirstPage?id=001D000000IRt53
```

Initially the contact detail page is not rendered, but when you click a contact name the page renders the appropriate detail view.

:::note
If you use the `id` parameter in a URL, it must refer to the same entity referred to in the standard controller.
:::

**See Also**

- [Controller Methods](/docs/platform/salesforce-pages-developers-guide/guide/pages-controller-methods.md)