As you know, under the hood there's no just date data in CRM.
When searching by DateTime fields in CRM, the operators
on-or-before will ignore the time component of your query and will just search by date. Advanced find doesn't give you a lot to work with in this regard.
To get around this, you should use the
You can use between both in FetchXML and QueryExpressions in C#:
var betweenCondition = new ConditionExpression("datefieldname", ConditionOperator.Between, lower, upper);
<filter type="or" > <condition attribute="datefieldname" operator="between" > <value> 2015-10-14T17:27:00+03:00 </value> <value> 2015-10-22T12:48:00+03:00 </value> </condition> </filter>
Keep in mind that CRM stores dates in UTC, provide your datetimes accordingly in FetchXml.