Retrieve top one record from CRM using early bound

Question

I want to retrieve top most record from my CRM entity using early bound query expression.

I have written it as:

QueryExpression opportunityProductsQuery = new QueryExpression
        {
            EntityName = PCSEPortal.oph_ophthalmicclaim.EntityLogicalName,
            ColumnSet = new ColumnSet("Name"),
            Criteria = new FilterExpression
            {
               new ConditionExpression
                        {
                            //condition
                        }
            }
        };
        return "";

But I am not sure how to write where condition and top 1 order by Desc condition here.

For where condition, I have column as Submission channel

- Logical name - oph_submissionchannel
- Schema Name  - oph_SubmissionChannel

and order by Guid or any unique id.

How to write query expression here? Or is there any other better option? I am trying to avoid FetchXML for this.

Answer 1

You can also use QueryExpression's TopCount property:

QueryExpression opportunityProductsQuery = new QueryExpression
{
    EntityName = PCSEPortal.oph_ophthalmicclaim.EntityLogicalName,
    TopCount = 1,
    ColumnSet = new ColumnSet("Name")...
};

Answer 2

You have to use PagingInfo to achieve this.

opportunityProductsQuery.PageInfo.Count = 1;

Read more. This example shows how to use LinkEntity, LinkCriteria, Sort Order Descending & PageInfo to get result.

    LinkEntity le = opportunityProductsQuery.AddLink(PCSEPortal.oph_submissionchannel.EntityLogicalName, “oph_submissionchannelid”, “2ndentityname2”);
    le.Columns = new ColumnSet(“oph_submissionchannelid”);
    le.LinkCriteria.AddCondition(“oph_submissionchannelid”, ConditionOperator.Equal, Guid);   //where condition
    opportunityProductsQuery.AddOrder(“modifiedon”, OrderType.Descending);
    opportunityProductsQuery.PageInfo = new PagingInfo();
    opportunityProductsQuery.PageInfo.Count = 1;
    opportunityProductsQuery.PageInfo.PageNumber = 1;

    EntityCollection entitycolls = service.RetrieveMultiple(equery);