0

What is the formal definition of a SQL identifier in the ISO/IEC 9075:2016 standard?

Most specifically, in the case of both regular and delimited identifiers, what limitations exist on:

  • Character set (UTF8?)
  • First character set
  • Subsequent character set
  • Length limits
0

1 Answer 1

4

You can look up the rules e.g. here

So a "regular" (i.e. "non-delimited") identifier must start with a <simple Latin letter> which is essentially only the characters a-z (either upper or lower case).

Then it maybe followed by an <SQL language identifier part> which is either a <simple Latin letter> or a <digit> or the <underscore>

To sum it up: a regular identifier must start with a letter from a-z, and can only contain letters, digits (0-9) and the underscore.

A regular expression to validate a simple identifier would be: [a-zA-Z][a-zA-Z0-9_]*

Mandating "simple latin letters" makes any multi-byte character set (e.g. UTF-8) invalid for use with a simple identifier.

Other character (e.g. a space) can only be used when using a "delimited" (aka "quoted") identifier which is enclosed in double quotes, e.g. "%foo bar$". As far as I know this is also true for multi-byte characters.

The allowed length of an identifier is discussed in this question: Does the SQL-1992 standard restrict naming identifiers to 18 characters?

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.