populate object where it contains values from another list

Question

In my object I have 3 properties:

    public String PlaceName{ get; set; }
    public Int32 PlaceId { get; set; }
    public Boolean IsChecked { get; set; }

I have a result with 5 rows being returns from my database (SQLPlaceALL).

• place A
• place B
• place C
• place D
• place E

These 5 results I always want to display. However, when I choose a contact, that contact could have one or more of these places in the results returned (sqlPlaceResults).

• place B
• place C

• place D

      var popPlace = from places in sqlPlaceResults.AsEnumerable()
                       join placeAll in sqlPlaceResultsAll.AsEnumerable() 
                          on places["PLACEID"] equals placeAll["PLACEID"]
                         select new Place
                         {
                             PlaceName = places["NAME"].ToString(),
                             PlaceId = (Int32)places["PLACEID"],
                             Ischecked = true
                         };
  

When I do this popPlace only contains the 3 items that sqlPlaceResults contains. I'd like my display to do something like this:

• place A
• place B - Checked
• place C - Checked
• place D - Checked
• place E

Answer 1

Something like this should work. You want to query all the places, and set IsChecked based on whether there are any matching sqlPlaceResults.

var popPlace = 
    from placeAll in sqlPlaceResultsAll.AsEnumerable()
    select new Place
    {
        placeName = regions["NAME"].ToString(),
        PlaceId = (Int32)regions["PLACEID"],
        Ischecked = sqlPlaceResults.AsEnumerable().Any(
            places => places["PLACEID"] == placeAll["PLACEID"])
    };

Answer 2

You want to do a left join it seems.

Here is an MSDN on how to do this

And here is your code modified into something similar from the article:

var popPlace = 
    from places in sqlPlaceResults.AsEnumerable()
        join placeAll in sqlPlaceResultsAll.AsEnumerable() 
            on places["PLACEID"] equals placeAll["PLACEID"] into placeAllVals
    from sub in placeAllVals.DefaultIfEmpty()
    select new Place
    {
        PlaceName = regions["NAME"].ToString(),
        PlaceId = (Int32)regions["PLACEID"],
        Ischecked = sub != null
    };