Character String Comparisons

You can enter character strings as validation checks for fields designated as character data types. Always enclose character string validation checks in double quotation marks, except for the LIKE operator, which accepts strings with single quotation marks.

Validation checks on character strings can include pattern‑matching characters. The following pattern‑matching characters are valid for all operators except the LIKE operator:

Character	Description
*	(Asterisk) Matches zero or more undefined characters. For example, S* equals any character string beginning with the letter S.
?	(Question mark) Matches exactly one undefined character. For example, T?P equals TAP, TIP, TOP, etc.
[...]	Matches any characters between the brackets including ranges. For example, [ACL]* equals any string that begins with A, C, or L. ?[N‑X] equals any two-character string that begins with any letter and has any letter between N and X as the second character.
%	(Percent sign) Matches zero or more undefined characters (similar to the * character described above).
_	(Underscore) Matches one undefined character (similar to the ? character described above).