You can use the following function
CREATE FUNCTION [dbo].[fnSplit](
@sInputList VARCHAR(8000)
, @sDelimiter VARCHAR(8000) = ','
) RETURNS @List TABLE (ID VARCHAR(8000))
BEGIN
DECLARE @sItem VARCHAR(8000)
WHILE CHARINDEX(@sDelimiter,@sInputList,0) <> 0
BEGIN
SELECT
@sItem=RTRIM(LTRIM(SUBSTRING(@sInputList,1,CHARINDEX(@sDelimiter,@sInputList,0)-1))),
@sInputList=RTRIM(LTRIM(SUBSTRING(@sInputList,CHARINDEX(@sDelimiter,@sInputList,0)+LEN(@sDelimiter),LEN(@sInputList))))
IF LEN(@sItem) > 0
INSERT INTO @List SELECT @sItem
END
IF LEN(@sInputList) > 0
INSERT INTO @List SELECT @sInputList
RETURN
END
The output can be verified like
select * from dbo.fnSplit('[12] [12] [13]',' ')
It will show
12
12
13