<string literal>
| <number literal>
| <date literal>
| <time literal>
| <monetary literal>
| <set literal>
| USER
| NULL
"문자 스트링 데이터 타입"을 참조한다.
<exact number literal>
| <approx number literal>
[ + | - ] <unsigned real literal>
<unsigned integer literal> [.<unsigned integer literal>
]
| <unsigned integer literal>
| <unsigned integer literal>
<exact number literal> [E|e] <integer literal>
[ + | - ] <unsigned integer literal>
One or more decimal digits.
<string literal> of form mm/dd/[yyyy].
<string literal> of form 'hh[:mm[:ss] ] [ampm]'.
$<unsigned real literal>
[<set specifier> {[value specification comma list>]}