Compare column value with the values of another column in Power Query

[Lainkito59]

Hi everyone, 

I have this table in Power Query and I want to check if the value in column ID is available in the column PARENT ID.
For example, the ID 12 is available in PARENT ID column so we can create a new column and put "AVAILABLE" and for the ID 6 put "NOT AVAILABLE". 
I want to do it in Power Query and not in Power BI because I need to import only the AVAILABLE values.

Thanks in advance for your support !

[wdx223_Daniel · Accepted solution]

=Table.AddColumn(YourTableName,"Custom",each if List.Contains(YourTableName[PARENT ID],[ID]) then "AVAILABLE" else null)