Leading Zero Before Time in SQL Server - sql

Question

I want to add a leading zero before time in (12 Hrs Format)
Example:
SELECT RIGHT('0000000'+CONVERT(VARCHAR(20), CONVERT(DATETIME, '01:00PM', 0), 100), 7)
The result is 1:00PM
I am expected result like 01:00PM
But, when I try below code it works
SELECT RIGHT('0000000'+'1:00PM',7)
I want to know why the first query not given the expected result.

Answer 1

Try with this
SELECT FORMAT (getdate(), 'hh:mmtt') as time
The result is: 07:30AM
SELECT FORMAT (CONVERT(DATETIME, '01:00PM', 0), 'hh:mmtt') as time
The result is : 01:00PM

Answer 2

If you run:
select '"' + CONVERT(VARCHAR(20), CONVERT(DATETIME, '01:00PM', 0), 100) + '"'
You will get:
"Jan 1 1900 1:00PM"
I'm not sure why you think that prepending '0000000' and taking the last seven characters would do what you want.
It is a little hard to figure out what you really want, because you are starting with a constant that has the format you want.
If you want a zero-padded 12-hour time format, you can use:
select right('0' + convert(varchar(255), convert(time, getdate()), 100), 7)

Answer 3

Just try it step by step to see what is happening:
SELECT CONVERT(DATETIME, '01:00PM', 0)
--> 1900-01-01T13:00:00Z
SELECT CONVERT(VARCHAR(20), CONVERT(DATETIME, '01:00PM', 0))
--> Jan 1 1900 1:00PM
SELECT '0000000'+CONVERT(VARCHAR(20), CONVERT(DATETIME, '01:00PM', 0))
--> 0000000Jan 1 1900 1:00PM
And the seven rightmost letters of the last expression are, obviously, 1:00PM.
As others have suggested, use FORMAT (SQL Server 2012 and above) instead:
SELECT FORMAT(CONVERT(DATETIME, '01:00PM', 0), 'hh:mmtt')
--> 01:00PM

Answer 4

This part of the code:
CONVERT(VARCHAR(20), CONVERT(DATETIME, '01:00PM', 0), 100)
will give you this result: Jan 1 1900 1:00PM
This part:
CONVERT(DATETIME, '01:00PM', 0)
will return this: 1900-01-01 13:00:00.000
What is the goal here ?
I agree with the option provided from #SANDEEP answer.
Check the demo