How to set a constraint on a field value in an ABAP table so that it can contain any of 'n' possible values? For example, if I am entering a weekday, it can have either of only 7 possible values. Is there a consistency check setting for this during table creation?
You can use domains for this purpose. Table field => Data Element => Domain. In the domain you can define possible values for that field. If your example with the weekdays is really what you need, than check out domain WEEKDAY in SE11.