BCP on Primary keys

I’m kinda new at SQL databases, so I wanna sumthing about primary keys.
Is it better to use PK that are integer. Or can you use a textfield as a PK.

For example i have a table ‘Groups’ with only Groupnames, they are unique. Groups has a 1->n relation with ‘Tables’. Tables has the following colums: Tablename, Create_priv, Retrieve_priv, Update_priv and Delete_priv. (actually it’s n->m relation but I don’t wanna complicate my question)
Can I use (in this case) the colums Group as a PK in Groups and Tablename as a PK in Tables? Or is it better to use an integer such as Group_ID and Table_ID??

In Filemaker I always used numbers as PK (example 2 in the attachement)…simply becoz I didn’t trust Filemaker enough

Are there any restrictions in using text as a PK. Filemaker had the restricition that it would only index the first 60 characters in portions of max 3x20 characters, so you could use max 3 words of max 20 characters as a PK.

See the attached file for more clarity.

the ‘better’ way is to always use integer pk’s

because in youre example. What happens if you use the group name (if it is a pk) as a foreignkey in another table. But then you want to rename the groupname?? Then also every FK must be renamed ..