Regex pattern to validate SQL identifier names
Returns a regular expression to validate unquoted SQL identifiers.
Valid SQL identifiers must begin with an alphabetic character followed by
alphanumeric characters or underscores "
Character string with regular expression.
The current implementation doesn't allow any other special characters in SQL identfiers or quoted SQL identifiers for safety reasons. In future releases, valid SQL identifiers might be defined depending on the target database system.
ORACLE Database SQL Language Reference.