CAML Query to get only non duplicates - sharepoint-2013

Question

My first goal is to get all items that has a status of 'Pending' in my sharepoint list. My code so far is like this :
using (var clientContext = new ClientContext(spSite.Trim()))
{
clientContext.Credentials = GetNetworkCredential();
var approvalLists = clientContext.Web.Lists.GetByTitle(approvalLibraryName);
CamlQuery query = new CamlQuery();
query.ViewXml = "<View>" +
"<Query>" +
"<Where>" +
"<Eq>" +
"<FieldRef Name='IsApproved'/><Value Type='Choice'>Pending</Value>" +
"</Eq>" +
"</Where>" +
"</Query>" +
"</View>";
ListItemCollection approvalListItem = approvalLists.GetItems(query);
clientContext.Load(approvalListItem);
clientContext.ExecuteQuery();
}
It is working but I then realize that a particular item can be inserted more than 1 in that list. So for example for item request_100, it can have one row for pending and another row for approved. So I need to only get those non duplicates items with status 'Pending'. Is it possible to have group by then fetch only those who have count = 1? Because I'm thinking if I could just load all items then manipulate it in using linq list. Or do you guys have another suggestion for this?

Answer 1

My first thought was indeed also using linq on the ItemCollection which should be working just fine.
But just a thought, if you select only the 'pending' rows, you won't get duplicates will you? Or can there be more than one item like 'request_100' with statusses 'Pending'?
Check this question which is alike to yours: https://sharepoint.stackexchange.com/questions/43262/how-to-use-groupby-in-caml-query