Get datetime between start and end datetime

DECLARE @StartDt datetime='2019-09-11 12:00.000';

DECLARE @EndDt datetime='2019-09-11 13:15.000';

SELECT *FROM tableName WHERE START_DATE BETWEEN @StartDt AND @EndDt AND End_Date BETWEEN @StartDt AND @EndDt;

 

If compare with GETDATE  

SELECT *FROM tableName WHERE GETDATE() BETWEEN @StartDt AND @EndDt;

You have to use "between" with "start" and "end" as like following

 

SELECT * FROM employee 
WHERE Start_Date BETWEEN '2019-09-11 12:00.000' AND '2019-09-11 13:15.000'
AND End_Date BETWEEN '2019-09-11 12:00.000' AND '2019-09-11 13:15.000';
 

I have also attached a script file