How to pass SQL date greater then or less then condition in ASP.NET C#

 ed.Date.ToString() == "15/08/2019 00:00:00"

select Batch_Code from MST_BATCH where batch_end_date <= '2020-03-24'

CASE WHEN ISNULL(Course_Entryon,'2022-01-01')  <= '2022-04-01' THEN

CASE when ISNULL(NSQF_duration_in_hour,0)=0 or NSQF_duration_in_hour=NULL or NSQF_duration_in_hour='' THEN Theory_duration_in_hour 

WHEN ISNULL(Theory_duration_in_hour,0)=ISNULL(NSQF_duration_in_hour,0) THEN ISNULL(NSQF_duration_in_hour,0) ELSE '' END

ELSE 

CASE when ISNULL(NSQF_Reimburse_duration_in_hour,0)=0 or NSQF_Reimburse_duration_in_hour=NULL or NSQF_Reimburse_duration_in_hour='' THEN Theory_duration_in_hour 

WHEN ISNULL(Theory_duration_in_hour,0)<ISNULL(NSQF_Reimburse_duration_in_hour,0) THEN ISNULL(NSQF_Reimburse_duration_in_hour,0)

WHEN ISNULL(Theory_duration_in_hour,0)>ISNULL(NSQF_Reimburse_duration_in_hour,0) THEN ISNULL(NSQF_Reimburse_duration_in_hour,0)

WHEN ISNULL(Theory_duration_in_hour,0)=ISNULL(NSQF_Reimburse_duration_in_hour,0) THEN ISNULL(NSQF_Reimburse_duration_in_hour,0) ELSE '' END 

END as Actual_CoursePeriod,