How to add comma seperated strings as column value

Basically, don't - it's very easy to do, but it's a total nightmare to work with whenever you have to make any changes. SQL string handling is pretty poor and you have to really mess about in order to do anything.
Instead, create a second table which links a Class value to a Resource ID, and have multiple entries in that.
In practice, what I would do is have three tables:
Resources:

Id
...

Classes:

Id
Room

ClassesInResource

Id
ResourceId
ClassId

And fill them:
Resources:

1      John     Smith
2      Mary     Jones

Classes:

1      Bedroom
2      Kitchen
3      Dining room
4      Lounge

ClassesInResource:

1      1      1
2      1      2
3      1      3
4      2      1
5      2      3
6      2      4

It may seem more complicated - and it is - but it's really very simple to use, and it makes later coding a lot, lot easier!