Create date using two dates

Here is the logic to create a date using two dates:

For eg:

We have 2 dates Tdate1 and Tdate2. And we want to create a new datetime using these 2 dates, in which we will take date part from Tdate1 and time part from Tdate2. So we can do this using  below query:

 Convert(datetime, CONVERT(VARCHAR(500), Tdate1, 110)
                                + ' '
                                + CONVERT(VARCHAR(50), Tdate2, 108) )

Compare dates :
if we have to check interval(day,month,year,min,hour) between 2 dates than we can use logic defined below:

MONTH:

Tdate1: 7 June 2013 00:00:00
Tdate2: 5 July 2013 00:00:00

select 'Difference',DATEDIFF(month, convert(datetime, Tdate1,Tdate2)
Result:  Difference,1

 MONTH:(-ve)
Tdate1: 7 June 2013 00:00:00
Tdate2: 5 May 2013 00:00:00

select 'Difference',DATEDIFF(month, convert(datetime, Tdate1,Tdate2)
Result:  Difference,-1

 YEAR:

Tdate1: 7 June 2013 00:00:00
Tdate2: 5 July 2013 00:00:00

select 'Difference',DATEDIFF(Year, convert(datetime, Tdate1,Tdate2)
Result:  Difference,0

 HOUR:
Tdate1: 7 June 2013 00:00:00
Tdate2: 7 June 2013 05:06:07

select 'Difference',DATEDIFF(Hour, convert(datetime, Tdate1,Tdate2)
Result:  Difference,5

 MINUTE:
Tdate1: 7 June 2013 00:00:00
Tdate2: 7 June 2013 05:06:07

select 'Difference',DATEDIFF(Minute, convert(datetime, Tdate1,Tdate2)
Result:  Difference,6

 SECOND:
Tdate1: 7 June 2013 00:00:00
Tdate2: 7 June 2013 05:06:07

select 'Difference',DATEDIFF(Second, convert(datetime, Tdate1,Tdate2)
Result:  Difference,7

Let me know if i am missing anything or we have to make any change in this Post.

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