Error Message:

Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding.

Reason:

Default execution timeout value in SQL Studio is 30 seconds

Solution:

Increase the execution & connection timeout value while opening new query window(File --> New --> Database Engine Query)

if a column in DB table is a datetime and you need to compare TIME only (without DATE) , there is no built in function for that.

Here is small Query to perform that task. The key is converting both to same Date

@time1 datetime  
@time2 datetime 
select @time1 = '1900-01-01 07:30:00.000',
 @time2 = '1899-12-30 07:30:00.000' 
-- This convert both @time1 & @time2 into same date (1900-01-01) such that you can compare the time. 
-- Note : Resuls is a datetime
select tm1 = dateadd(day, datediff(day, 0, @time1) * -1, @time1),  
-- This uses convert function + substring to extract the time. 
-- Note : Result will be a varchar
tm2 = dateadd(day, datediff(day, 0, @time2) * -1, @time2)
select tm1 = substring(convert(varchar(25), @time1, 121), 12, 12), tm2 = substring(convert(varchar(25), @time2, 121), 12, 12) 
---Comapre tm1 & tm2 

Thanks to tip from "khtan" of SqlTeam