How do I tell the prefilter field to show all values?
If the prefilter is not a select, then an empty value should be entered.
However, for the select type, an empty value can be significant — therefore, there is a special value *ALL*, which means that all values should be displayed.
How do I filter by empty values?
If you need to filter by empty values, this can be done using a select field type, one of the values of which will be equal to empty.
Empty can be included with the parameter Empty (). You can override the name of the empty option through Name for Empty Option ().
How can I prevent any rows from being shown?
This is possible for selects. You need to activate the value Nothing (NONE). If the prefilter field is connected to the row part, it will be highlighted in red when *NONE* is selected.
How will the filtering be done if the prefilter has a single selection and the string part has multiple selections?
By value entry.
How will the filtering be done if there are multiple selections in the prefilter and in the rows part?
At any intersection.