Column validation- User must enter A or B as first character

Question

I am trying to create a validation formula which will verify that the user entered A or B as the first character in the column.

Can't seem to get the formula right. Can anyone help?

[EDIT] One thing I didn't realise is that column names with spaces should be wrapped in square brackets in the formulas below e.g. [Staff Name]

Answer 1

Try

=OR((CODE(MID(Title,1,1))=65),(CODE(MID(Title,1,1))=66))

This looks at the first letter entered and compares it to ASCII code 65 or 66 (A or B) and returns true if it matches one of these and thus passes validation

Andy

Answer 2

Add below validation formula in Validation Settings,

=OR(LEFT(Title,1)="a",LEFT(Title,1)="b")

Replace 'Title' with your column name. Please note that the formula is not case-sensitive. So it would return true for column values starting with a,A,b,B.

Refer below article for more examples,

SharePoint Column Validation Examples