# How do I place leading zeros for numbers less than 10 without affecting those 10+?

Probably a newb question, but...

I have a table with a VARCHAR field containing numbers 1 through 300. I need to place a leading zero in front of any numbers less than 10 while retaining the original number if it is 10 or greater (i.e. 1=01, 10=10 and 300=300).

``````SELECT DISTINCT RIGHT('0'+CONVERT(VARCHAR,[FacilityCode]),3) FROM...
``````

This returns 1=01, 10=010 and 300=300 (using the same examples as above)

EDIT: I'm trying to do this within a query so that I can do lookups without altering either table.

Can someone lend a brother a hand here? My brain just ain't working.

• Any particular reason you don't want `1` to be `001` ? Jul 24 '14 at 15:20
• RolandoMySQLDBA - The related table has varchar values which follow the example above. Mark, I'm using MSSQL 2008 r2. All... I'm trying to do this through a query in order to select items in a related table which formats the numbers (which are actually varchars) in the manner illustrated above. Jul 24 '14 at 15:32

The safest way is probably to only add zeroes when the length of the column is 1 character:

``````UPDATE
Table
SET
MyCol = '0' + MyCol
WHERE
LEN(MyCol) = 1;
``````

This will cover all numbers under 10 and also ignore any that already have a leading 0.

EDIT

To just select the data try:

``````SELECT
MyColPadded = CASE WHEN LEN(MyCol) = 1 THEN '0' + MyCol ELSE MyCol END
FROM
MyTable;
``````

If you wanted a 3 digit number try this.

``````SELECT DISTINCT
RIGHT('000'+CAST(ISNULL([FacilityCode],0) AS VARCHAR),3)
FROM...
``````

Result: 1=001, 10=010 and 300=300

An 8 digit number would be:

``````SELECT DISTINCT
RIGHT('00000000'+CAST(ISNULL([FacilityCode],0) AS VARCHAR),8)
FROM...
``````

Result: 1=00000001, 10=00000010 and 300=00000300

This has the advantage of working with subqueries:

``````SELECT t_lac.FORCE_OVERWRITE
, ISNULL(lay.ID,0) AS lacIDLayout
--, t_lac.lacName
, CASE WHEN t_lac.lacIDControlType = 18
THEN 'PAN' + RIGHT('000' + CAST(ISNULL((SELECT ID FROM Layout l WHERE l.layName = t_lac.lacName),0) AS VARCHAR),3) + '_' + t_lac.lacName
ELSE t_lac.lacName
END AS lacName
, t_lac.lacIDControlType
, t_lac.lacStyle
FROM @T_LayoutControl t_lac
LEFT JOIN Layout lay ON lay.layName = t_lac.layName
``````

(it looks from your example code that you are using MS SQL Server, but you should add an appropriate tag (and/or body text) to your question to indicate this if so, or if not which DBMS you are actually using)

Any of the options above should work fine, I would generally use the "prefix 0s then use `RIGHT()` option as you have but the others are perfectly valid), but a word of warning if you expect new rows (or updates to existing rows) to contain low numbers - if that is possible then you will end up with unpadded values creeping back in. To avoid this you could use either an `AFTER` or `INSTEAD OF` trigger to force values into the right format as they are inserted/updated to stop the problem coming back (without needing to change all code points that save to that table). Be careful to verify performance though: triggers can be very powerful but it is also easy to create a performance nightmare with them.

You can use a case statement for this, if it must be formatted in the database and you can't persist it.

``````Select case when len(facilityCode) = 1 then
'0' else '' end + facilityCode as facilityCode
From YourTable
``````

It sounds like you are doing this as a FK, if so you can't have a FK constraint on a calculation. To make doing the join easier, you might consider a calculated column.

`````` ALTER TABLE yourTable
case when len(facilityCode) = 1 then '0' else '' end + facilityCode);
``````
``````UPDATE MyTable
SET MyColumn = '0' + Mycolumn
WHERE MyColumn < '10'
AND MyColumn NOT LIKE '0%';
``````
• The OP stated that the minimum value is 1, but in general, if you want at least two digits, and you have zero, you do want to add another zero, so I would use `LEN` (as in JNK's answer) rather than `LIKE`.
– hvd
Jul 24 '14 at 19:47
• The logic behind the answer is sane but the answer is not correct for a very different reason than the above comments. `MyColumn` is a varchar, so the condition `MyColumn < '10'` will not result in `TRUE` when the value in the column is `'2'` or `'3'` or ... `'9'`. For char values `'9' < '10'` is false. Jul 25 '14 at 9:32
• Agree with @ypercube. You could change the first comparison to `MyColumn < 10` but that might break as we don't know if `MyColumn` is guaranteed to ever contain only numbers. Jul 25 '14 at 10:16
``````declare @num varchar(50) = '7'
select case when @num<100
then RIGHT('00'+ CONVERT(VARCHAR(50),@num),2)
else CONVERT(varchar(50),@num) end
``````
• welcome to the site. Along with code try to write down some statement for better understanding. Feb 24 '18 at 8:54
• Also - why use 100 as a cut-off, when 10 would be a better one - only values from 0 through 9 should have an extra zero added. Mar 27 '18 at 14:43