Basically, when you create the table the records will be displayed in the same order as in the datasource. Then if you apply sorting by the string column, all the strings will be sorted and the dates will be displayed as in the datasource. If there are multiple dates that correspond to the same string, then you can add second sorting based on the dates.
For more information, take a look at Sorting table Data article. You can also check the attached sample report.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items