Characters
The basic symbols of keywords and operators in the SQL language are characters that are classified as letters, digits, or special characters.
- A letter is any of the 26 uppercase (A through Z) and 26 lowercase (a through z) letters of the English alphabet.1
- A digit is any one of the characters 0 through 9.
- A special character is any character other than a letter or a digit.
1 Letters also include three code points reserved as alphabetic
extenders for national languages ($, #, and @ in the United States).
These three code points (X'5B', X'7B', and X'7C') should be avoided
because they represent different characters depending on the CCSID.