Check for Alpha Only

This is a way to restrict data entry to alpha if you are using a release below 10G. It's not particularly pretty, but it works.

I'm basically translating all alpha characters to spaces, and then trimming them out,which of course, leaves everything else. Then I check for a length. Remove the UPPER if you don't want lower case.

Create Table Testalpha
    (Alphaonly  Varchar2(10)
                Constraint Ck_Alphaonly Check
                    (Length
                          (Trim
                              (Translate
                                       (Upper(alphaonly),
                                       'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
                                       ' '
                                        )
                               )
                         ) is null
                     )
     );

In 10G, you can use the REGEXP functions:

Create Table Testalpha
    (Alphaonly  Varchar2(10)
                Constraint Ck_Alphaonly Check
                    (Regexp_Like(AlphaOnly, '^[[:alpha:]]+$')
                     )
     );