Am using the grid feature in the form to show multiple values from the database/

The check-box in the grid will return an array of boolean. Loop through the boolean using doForEach() function OR MNI in order to get the selected row/element. You can use the displayValue function here to select items that were 'selected' and use this in the subsequent form.

Another option is to use the paging grid component, based on what I am easing about your scenario. The paging grid can be populated using a query rule (data from data source) and if you save the selection into an ac, it will give you a radio button or check boxes if you are saving into a single or multi. The primary id will be saved into the variable, then you can execute a query rule for example based on the stored value to get more details.

am still not clear ..I get the values in the next form but each parameter has multiple values...now I want only single value(that the user has selected) to reflect...am a newbie in appian..I assume javascript can help but am not sure

You don't need to use JS. On the form with the paging grid, are you saving the selection into an ac, that is not a multiple? If you save it into an ac and then into a pv, you can use that pv on the next form to display data, execute a query rule to get more data about that one record, etc. hope that helps!

I'm struggling with the same thing, but on a regular grid, not paging. I'm trying to allow the user to select more than one item. There are, e.g, two fields, first name and last name, that I need to display. So after the selection, I have an array of booleans, an array of first names, and an array of last names. So, say I have "true, true, false," "Joe, null, Jerry", "Smith, Jones, Doe." Since the If statement requires a value if false, then after I select the trues, I have "Joe, null, null" and "Smith, Jones, null." If I don't filter out the nulls (and by the way, I can't get filternulls to work so I'm using filterlist), I don't have just the selected data. If I do, then one of the arrays will be short. I'm still trying things, but if you could provide a few more specifics on how to go about this, I'd appreciate it.

Duh, I could put X or something instead of null. But anyway, I keep feeling like I must be going about this the wrong way.

To save someone else too many hours of work, I'm going to record how I finally got this to work. All variables mentioned are multiples. The first rule returns the values for the selections: displayvalue(true(),ri!arrayToSearch,ri!replacementArray,null). It is used with doforeach in node outputs of the form where the selection is made (doforeach("rule1",ac!selections,pv!authorLast_text) to save the lastname in the selected row to a new PV, selectedLast; nonselected rows have empty values in selectedLast. Second rule (=ri!input<>"") removes the empty values from selectedLast and is used in a script task following the selection form [filterlist("rule2",pv!selectedLast)]. Even though the first rule says to return null if not found, the empty values are not nulls and need to be removed by filterlist instead of filternulls.