Download the attachment 203516 [details] (csv file from bug 169036) to your PC.
Start a new spreadsheet. Define a database range "myImport" for range $Sheet1.$A$2:$C$101 and make sure that "contains column labels" is checked (that is in Options).
Menu > Data > Data Provider.
In that dialog do these:
* in section `Source` select the database range "myImport".
* Click on the `Browse` button and select the downloaded csv file.
* in section `Transformations` select entry `Split Column` and click on `Add` button. You get additional fields.
* In field `Separator string` insert a pipe symbol, that is | . In field `Column index` enter 1. Click the `Apply` button below the Preview.
* in section `Transformations` click on `Add` again to insert the next `Split Column` transformation.
* Enter the pipe symbol in the field `Separator string` and value 2 in `Column index` field. Click the `Apply` button below the Preview.
* In section `Transformations` select entry `Sort columns` and click on `Add`
* Select `Ascending order` and set column index to 3. Click the `Apply` button.

Error: The preview does not show a sort.

Click on OK button.

You get data sorted ascending in column C, but the label row is treated as ordinary record although your database range has set "contains column labels".

The sort transformation should examine the setting in the target range or should provide a checkbox itself, whether to include the first row in sorting.

As workaround, the sorting could be always as if "contains column labels" is checked, because it is very likely that the to be imported data has labels.