문자열 함수

• $concat
• $substr
• $toLower / $toUpper
• $strcasecmp

산술 함수

• $add / $subtract
• $divide / $mod / $multiply

날짜/시간

• $dayOfYear / $dayOfMonth / $dayOfWeek
• $year / $month / $week
• $hour / $minute / $second / $millisecond