SQL Server Padding 0's with RIGHT Not Working - sql-server

Question

I am using SQL Server 2008.
I have a varchar(30) column which holds check numbers. If the payment was made using a credit card, checknbr will be a zero-length string. I need to pad this data with leading zeroes such that the entire output is ten digits long. If there is no check number, it should just be ten zeroes.
Here is the data I would like to see:
0000000000
0000000000
0000000114
0000000105
0000000007
Here is the query I have been using and am stuck on:
SELECT RIGHT((CASE
WHEN LEN(checknbr) = 0 THEN '0000000000'
ELSE '0000000000'+checknbr
END),10) as checknbr
FROM payhistory
WHERE number = 12345678
And this is what I get:
0000000000
0000000000
114
105
7
Trying another way:
SELECT RIGHT('0000000000'+checknbr,10)
FROM payhistory
WHERE number = 3861821
And I get the same results. Oddly enough, I have a varchar(10) column where
RIGHT('0000'+EDC.DatabaseNumber,4)
yields exactly the results I am after. What am I missing here? Something about a quirk with the RIGHT function?
Thanks in advance

Answer 1

If you are using SQL server 2012 or up try the following:
SELECT RIGHT(CONCAT('0000000000', checknbr), 10)
Concat will automatically convert NULL values to empty strings, removing the need for extra checks.
By the way, the issue you're having is the fact that your query still sees checknbr as a number instead of a varchar value. Casting it to varchar will solve that for you.
EDIT SQL Server 2008:
Since you have a VARCHAR column with no NULL values the only thing that still comes to mind are trailing spaces. Try:
SELECT RIGHT('0000000000' + RTRIM(checknbr), 10);

Answer 2

using cast() or convert() to convert checknbr to a character value will solve the implicit conversion of '0000000000' to the integer 0.
select right('0000000000'+convert(varchar(10),checknbr),10)
from payhistory
where number = 3861821
If checknbr can be null and you want it to return as '0000000000', then you can wrap it in coalesce() or isnull():
select right('0000000000'+isnull(convert(varchar(10),checknbr),''),10)
from payhistory
where number = 3861821
If checknbr is not a number, but varchar(30), then (as Jens points out), you may have padded spaces that need to be trimmed:
rextester demo: http://rextester.com/IRLV83801
create table payhistory (checknbr varchar(30));
insert into payhistory values ('0'), ('1'), (' 0'), ('0 '),(' ');
select checknbr = right('0000000000'+checknbr,10)
from payhistory
returns:
+------------+
| checknbr |
+------------+
| 0000000000 |
| 0000000001 |
| 0 |
| 0 |
| |
+------------+
And if you trim the padded spaces:
select checknbr = right('0000000000'+ltrim(rtrim(checknbr)),10)
from payhistory
returns:
+------------+
| checknbr |
+------------+
| 0000000000 |
| 0000000001 |
| 0000000000 |
| 0000000000 |
| 0000000000 |
+------------+