How to trim string (with Ideographic space U+3000) in sql server? - sql

Question

I have to trim Japanese characters string which has double byte space at start of string and end of string.
I have to do this by procedure of SQL server 2016.
For Example,
SELECT LTRIM(RTRIM(' A A '))
above one is working perfect
But Problem is in bellows line
SELECT LTRIM(RTRIM('　A　A　'))
i want output of above one is 'A　A'
Have any idea, how to do this ?

Answer 1

Adapted SQL from OP's post:
SELECT LTRIM(RTRIM(REPLACE('　A　A　', ' ', ' ')))
Screenshot with result:

Answer 2

The space in that string is the Ideographic space (U+3000) Unicode character, which LTRIM and RTRIM don't recognize as whitespace. Even TRIM in SQL Server 2017 won't recognize it unless it's specified explicitly.
Another problem is that this character is outside the normal range of characters and can't appear in a varchar field or value. This leads to inconsistent results between SQL Server versions. In SQL Server 2014 it will even appear as a ?. In later versions LTRIM/RTRIM may or may not work without emitting the error character. I don't have access to all versions to test this.
In SQL Server 2017 it's possible to explicitly specify the trimmed character, eg :
select trim(N'　' from N'　A　A　')
This produces A　A.
In previous versions, PATINDEX can be used to find the locations of the first and last non-space positions :
declare #str nvarchar(10)=N'　A　A　';
declare #start int=PATINDEX(N'%[^　]%',#str)
declare #end int=PATINDEX(N'%　',#str)
SELECT SUBSTRING(#str,#start,#end-#start)
The pattern N'%[^　]%' finds the first non-U+3000 character in the string. N'%　' finds the position of the last one. SUBSTRING(#str,#start,#end-#start) extracts the content between the two positions.
The result is:
A　A

Answer 3

I got solution
Thank you so much for your efforts.
Please use this function for double byte space remove.
CREATE FUNCTION [RTRIMBYTE](#AV_VALUE NVARCHAR(MAX))
RETURNS NVARCHAR(MAX)
AS
BEGIN
DECLARE #AV_RETURN NVARCHAR(MAX) = #AV_VALUE;
WHILE DATALENGTH(#AV_RETURN) > 0 AND RIGHT(#AV_RETURN, 1) in (' ', '　')
SET #AV_RETURN = LEFT(#AV_RETURN, LEN('X' + #AV_RETURN + 'X') -3 ) ;
RETURN #AV_RETURN;
END;