An ordinary identifier must begin with a letter and contain only letters,
underscore characters (_), and digits. The permitted letters and digits include
all Unicode letters and digits, but does
not attempt to ensure that the characters in identifiers are valid in the
database's locale.
delimited identifiersdefinitionA
delimited identifier can contain any characters within the double quotation
marks. The enclosing double quotation marks are not part of the identifier;
they serve only to mark its beginning and end. Spaces at the end of a delimited
identifier are insignificant (truncated). translates
two consecutive double quotation marks within a delimited identifier as one
double quotation mark-that is, the "translated" double quotation mark becomes
a character in the delimited identifier.
Periods within delimited identifiers are not separators but are part of
the identifier (the name of the dictionary object being represented).
So, in the following example: "A.B"
is a dictionary object, while "A"."B"
is a dictionary object qualified by another dictionary object (such as
a column named "B" within the table "A").