How to remove white space characters from a string in SQL Server

问题

I'm trying to remove white spaces from a string in SQL but LTRIM and RTRIM functions don't seem to work?

Column:

[ProductAlternateKey] [nvarchar](25) COLLATE Latin1_General_CS_AS NULL

Query:

select REPLACE(ProductAlternateKey, ' ', '@'),
       LEN(ProductAlternateKey),
       LTRIM(RTRIM(ProductAlternateKey))      AS LRTrim,
       LEN(LTRIM(RTRIM(ProductAlternateKey))) AS LRLen,
       ASCII(RIGHT(ProductAlternateKey, 1))   AS ASCIIR,
       ASCII(LEFT(ProductAlternateKey, 1))    AS ASCIIL,
       ProductAlternateKey
from DimProducts
where ProductAlternateKey  like '46783815%'

Result:

|  COLUMN_0 | COLUMN_1 | LRTrim | LRLen | ASCIIR | ASCIIL | PRODUCTALTERNATEKEY |
---------------------------------------------------------------------------------
|  46783815 |        8 | 46783815|     8|   53   |   52   |            46783815 |
| 46783815  |        10|46783815  |   10|   10   |   52   |           46783815  |

Can it be other symbols if LTRIM and RTRIM are not working, like "Enter"?

回答1:

Using ASCII(RIGHT(ProductAlternateKey, 1)) you can see that the right most character in row 2 is a Line Feed or Ascii Character 10.

This can not be removed using the standard LTrim RTrim functions.

You could however use (REPLACE(ProductAlternateKey, CHAR(10), '')

You may also want to account for carriage returns and tabs. These three (Line feeds, carriage returns and tabs) are the usual culprits and can be removed with the following :

LTRIM(RTRIM(REPLACE(REPLACE(REPLACE(ProductAlternateKey, CHAR(10), ''), CHAR(13), ''), CHAR(9), '')))

If you encounter any more "white space" characters that can't be removed with the above then try one or all of the below:

--NULL
Replace([YourString],CHAR(0),'');
--Horizontal Tab
Replace([YourString],CHAR(9),'');
--Line Feed
Replace([YourString],CHAR(10),'');
--Vertical Tab
Replace([YourString],CHAR(11),'');
--Form Feed
Replace([YourString],CHAR(12),'');
--Carriage Return
Replace([YourString],CHAR(13),'');
--Column Break
Replace([YourString],CHAR(14),'');
--Non-breaking space
Replace([YourString],CHAR(160),'');

This list of potential white space characters could be used to create a function such as :

Create Function [dbo].[CleanAndTrimString] 
(@MyString as varchar(Max))
Returns varchar(Max)
As
Begin
    --NULL
    Set @MyString = Replace(@MyString,CHAR(0),'');
    --Horizontal Tab
    Set @MyString = Replace(@MyString,CHAR(9),'');
    --Line Feed
    Set @MyString = Replace(@MyString,CHAR(10),'');
    --Vertical Tab
    Set @MyString = Replace(@MyString,CHAR(11),'');
    --Form Feed
    Set @MyString = Replace(@MyString,CHAR(12),'');
    --Carriage Return
    Set @MyString = Replace(@MyString,CHAR(13),'');
    --Column Break
    Set @MyString = Replace(@MyString,CHAR(14),'');
    --Non-breaking space
    Set @MyString = Replace(@MyString,CHAR(160),'');

    Set @MyString = LTRIM(RTRIM(@MyString));
    Return @MyString
End
Go

Which you could then use as follows:

Select 
    dbo.CleanAndTrimString(ProductAlternateKey) As ProductAlternateKey
from DimProducts

回答2:

In that case, it isn't space that is in prefix/suffix.
The 1st row looks OK. Do the following for the contents of 2nd row.

ASCII(RIGHT(ProductAlternateKey, 1))

and

ASCII(LEFT(ProductAlternateKey, 1))

回答3:

There may be 2 spaces after the text, please confirm. You can use LTRIM and RTRIM functions also right?

LTRIM(RTRIM(ProductAlternateKey))

Maybe the extra space isn't ordinary spaces (ASCII 32, soft space)? Maybe they are "hard space", ASCII 160?

ltrim(rtrim(replace(ProductAlternateKey, char(160), char(32))))

回答4:

How about this?

CASE WHEN ProductAlternateKey is NOT NULL THEN
CONVERT(NVARCHAR(25), LTRIM(RTRIM(ProductAlternateKey))) 
FROM DimProducts
where ProductAlternateKey  like '46783815%'

回答5:

Looks like the invisible character -

ALT+255

Try this

select REPLACE(ProductAlternateKey, ' ', '@')
--type ALT+255 instead of space for the second expression in REPLACE 
from DimProducts
where ProductAlternateKey  like '46783815%'

Raj

Edit: Based on ASCII() results, try ALT+10 - use numeric keypad

回答6:

Remove new line characters with SQL column data

Update a set  a.CityName=Rtrim(Ltrim(REPLACE(REPLACE(a.CityName,CHAR(10),' '),CHAR(13),' ')))
,a.postalZone=Rtrim(Ltrim(REPLACE(REPLACE(a.postalZone,CHAR(10),' '),CHAR(13),' ')))  
From tAddress a 
inner Join  tEmployees p  on a.AddressId =p.addressId 
Where p.MigratedID is not null and p.AddressId is not null AND
(REPLACE(REPLACE(a.postalZone,CHAR(10),'Y'),CHAR(13),'X') Like 'Y%' OR REPLACE(REPLACE(a.CityName,CHAR(10),'Y'),CHAR(13),'X') Like 'Y%')

来源：https://stackoverflow.com/questions/14211346/how-to-remove-white-space-characters-from-a-string-in-sql-server