date diff sql

1DECLARE 
2    @start_dt DATETIME2= '2019-12-31 23:59:59.9999999', 
3    @end_dt DATETIME2= '2020-01-01 00:00:00.0000000';
4
5SELECT 
6    DATEDIFF(year, @start_dt, @end_dt) diff_in_year, 
7    DATEDIFF(quarter, @start_dt, @end_dt) diff_in_quarter, 
8    DATEDIFF(month, @start_dt, @end_dt) diff_in_month, 
9    DATEDIFF(dayofyear, @start_dt, @end_dt) diff_in_dayofyear, 
10    DATEDIFF(day, @start_dt, @end_dt) diff_in_day, 
11    DATEDIFF(week, @start_dt, @end_dt) diff_in_week, 
12    DATEDIFF(hour, @start_dt, @end_dt) diff_in_hour, 
13    DATEDIFF(minute, @start_dt, @end_dt) diff_in_minute, 
14    DATEDIFF(second, @start_dt, @end_dt) diff_in_second, 
15    DATEDIFF(millisecond, @start_dt, @end_dt) diff_in_millisecond;

1SELECT DATEDIFF(year, '2017/08/25', '2011/08/25') AS DateDiff;

1SELECT (END_DATE - START_DATE) Days-Total FROM MyTable
2/*this works for oracle sql*/