Copy every entry from TableA to TableB where the ID is in a textfile containing a list of IDs
The easiest way I know of is creating a table in tempdb with a single column (id for instance), then expand the tempdb node in SSMS and find the table. Right click and select "Edit top 200 rows". 

A grid will appear. Select the whole first row with the row header on the left, then paste the whole contents of the file.

BCP is an alternative way to load the file contents to the destination table. In this case I don't find it any way easier than copying and pasting the file contents in SSMS.

You could also use OPENROWSET or other techniques to reference the file directly in your query, but that requires copying the file to the server or messing with permissions: too much hassle for a one-off task.