EXTRACT 연산자는 날짜/시간 값을 반환하는 연산식 date-time_argument 중 일부분을 추출하여 INTEGER 타입으로 반환한다.
EXTRACT ( field FROM date-time_argument )
field :
• YEAR
• MONTH
• DAY
• HOUR
• MINUTE
• SECOND
• MILLISECOND
date-time_argument :
• expression
SELECT EXTRACT(MONTH FROM DATETIME '2008-12-25 10:30:20.123' );
extract(month from datetime '2008-12-25 10:30:20.123')
=========================================================
12
SELECT EXTRACT(HOUR FROM DATETIME '2008-12-25 10:30:20.123' );
extract(hour from datetime '2008-12-25 10:30:20.123')
=========================================================
10
SELECT EXTRACT(MILLISECOND FROM DATETIME '2008-12-25 10:30:20.123' );
extract(millisecond from datetime '2008-12-25 10:30:20.123')
=========================================================
123