Removing leading zeros in a string in sqlserver - sql

Question

I want to remove leading zeros for a varchar column. Actually we are storing version information in a column. Find below example versions.
2.00.001
The output would be : 2.0.1
Input : 2.00.00.001
The output would be: 2.0.0.1
Input : 2.00
The output would be : 2.0
The dots in the version column not constant. It may be two or three or four
I found some solutions in google but those are not working. Find below are the queries I tried.
SELECT SUBSTRING('2.00.001', PATINDEX('%[^0 ]%', '2.00.001' + ' '), LEN('2.00.001'))
SELECT REPLACE(LTRIM(REPLACE('2.00.001', '0', ' ')),' ', '0')
Please suggest me the best approach in sqlserver.

Answer 1

One way is to use a string splitting function with cross apply, for xml path, and stuff.
For an explanation on how stuff and for xml works together to concatenate a string from selected rows, read this SO post.
Using a string splitting function will enable you to convert each number part of the string to int, that will remove the leading zeroes. Executing a select statement on the result of the string splitting function will enable you to get your int values back into a varchar value, seperated by dot.
The stuff function will remove the first dot.
Create the string splitting function:
CREATE FUNCTION SplitStrings_XML
(
#List NVARCHAR(MAX),
#Delimiter NVARCHAR(255)
)
RETURNS TABLE
WITH SCHEMABINDING
AS
RETURN
(
SELECT Item = y.i.value('(./text())[1]', 'nvarchar(4000)')
FROM
(
SELECT x = CONVERT(XML, '<i>'
+ REPLACE(#List, #Delimiter, '</i><i>')
+ '</i>').query('.')
) AS a CROSS APPLY x.nodes('i') AS y(i)
);
GO
I've chosen to use an xml based function because it's fairly simple. If you are using 2016 version you can use the built in string_split function. For earlier versions, I would stronly suggest reading Aaron Bertrand's Split strings the right way – or the next best way.
Create and populate sample table (Please save us this step in your future questions)
DECLARE #T AS TABLE
(
col varchar(20)
)
INSERT INTO #T VALUES
('2.00.001'),
('2.00.00.001'),
('2.00')
The query:
SELECT col, result
FROM #T
CROSS APPLY
(
SELECT STUFF(
(
SELECT '.' + CAST(CAST(Item as int) as varchar(20))
FROM SplitStrings_XML(col, '.')
FOR XML PATH('')
)
, 1, 1, '') As result
) x
Results:
col result
2.00.001 2.0.1
2.00.00.001 2.0.0.1
2.00 2.0
You can see it in action on this link on rextester

Answer 2

No need for Split/Parse Function, and easy to expand if there could be more than 5 groups
Declare #YourTable table (YourCol varchar(25))
Insert Into #YourTable Values
('2.00.001'),
('2.00.00.001'),
('2.00')
Update #YourTable
Set YourCol = concat(Pos1,'.'+Pos2,'.'+Pos3,'.'+Pos4,'.'+Pos5)
From #YourTable A
Cross Apply (
Select Pos1 = ltrim(rtrim(xDim.value('/x[1]','int')))
,Pos2 = ltrim(rtrim(xDim.value('/x[2]','int')))
,Pos3 = ltrim(rtrim(xDim.value('/x[3]','int')))
,Pos4 = ltrim(rtrim(xDim.value('/x[4]','int')))
,Pos5 = ltrim(rtrim(xDim.value('/x[5]','int')))
From (Select Cast('<x>' + replace((Select replace(A.YourCol,'.','§§Split§§') as [*] For XML Path('')),'§§Split§§','</x><x>')+'</x>' as xml) as xDim) as A
) B
Select * from #YourTable
Returns
YourCol
2.0.1
2.0.0.1
2.0

Answer 3

Easy, fast, compatible and readable way – without tables or XML tricks.
Correctly handles all cases including empty string, NULL, or numbers like 00100.
Supports unlimited number of groups. Runs on all SQL Server versions.
Step 1: Remove leading zeros from all groups.
Step 2: Place single zero to groups where no digits remained.
[Edit: Not sure why it was downvoted twice. Check the solution: ]
The function:
CREATE FUNCTION dbo.fncGetNormalizedVersionNumber(#Version nvarchar(200))
RETURNS nvarchar(200) AS
BEGIN
-- Preprocessing: Surround version string by dots so all groups have the same format.
SET #Version = '.' + #Version + '.';
-- Step 1: Remove any leading zeros from groups as long as string length decreases.
DECLARE #PreviousLength int = 0;
WHILE #PreviousLength <> LEN(#Version)
BEGIN
SET #PreviousLength = LEN(#Version);
SET #Version = REPLACE(#Version, '.0', '.');
END;
-- Step 2: Insert 0 to any empty group as long as string length increases.
SET #PreviousLength = 0;
WHILE #PreviousLength <> LEN(#Version)
BEGIN
SET #PreviousLength = LEN(#Version);
SET #Version = REPLACE(#Version, '..', '.0.');
END;
-- Strip leading and trailing dot added by preprocessing.
RETURN SUBSTRING(#Version, 2, LEN(#Version) - 2);
END;
Usage:
SELECT dbo.fncGetNormalizedVersionNumber('020.00.00.000100');
20.0.0.100
Performance per 100,000 calculations:
solution using helper function + helper tables + XML: 54519 ms
this solution (used on table column): 2574 ms (→ 21 times faster) (UPDATED after comment.)

Answer 4

For SQL Server 2016:
SELECT
STUFF
((SELECT
'.' + CAST(CAST(value AS INT) AS VARCHAR)
FROM STRING_SPLIT('2.00.001', '.')
FOR XML PATH (''))
, 1, 1, '')
According to this: https://sqlperformance.com/2016/03/sql-server-2016/string-split
It's the fastest way :)
Aaron Bertrand knows it's stuff.
For an interesting and deep read about splitting strings on SQL Server plese read this gem of knowledge: http://www.sqlservercentral.com/articles/Tally+Table/72993/
It has some clever strategies

Answer 5

I am not sure this is what you are looking for but you can give a go, it should handle up to 4 zeros.
DECLARE #VERSION NVARCHAR(20) = '2.00.00.001'
SELECT REPLACE(REPLACE(REPLACE(#VERSION, '0000','0'),'000','0'),'00','0')
2.0.0.01
SET #VERSION = '2.00.00.01'
SELECT REPLACE(REPLACE(REPLACE(#VERSION, '0000','0'),'000','0'),'00','0')
2.0.0.01
SET #VERSION = '2.000.0000.0001'
SELECT REPLACE(REPLACE(REPLACE(#VERSION, '0000','0'),'000','0'),'00','0')
2.0.0.01

Answer 6

Try this one
SUBSTRING(str_col, PATINDEX('%[^0]%', str_col+'.'), LEN(str_col))

Answer 7

Here is another sample:
CREATE TABLE #tt(s VARCHAR(15))
INSERT INTO #tt VALUES
('2.00.001'),
('2.00.00.001'),
('2.00')
SELECT t.s,STUFF(c.s,1,1,'') AS news FROM #tt AS t
OUTER APPLY(
SELECT '.'+LTRIM(z.n) FROM (VALUES(CONVERT(XML,'<n>'+REPLACE(t.s,'.','</n><n>')+'</n>'))) x(xs)
CROSS APPLY(SELECT n.value('.','int') FROM x.xs.nodes('n') AS y(n)) z(n)
FOR XML PATH('')
) c(s)
s news
--------------- -----------
2.00.001 2.0.1
2.00.00.001 2.0.0.1
2.00 2.0