In a SELECT statement(MS SQL) how do you trim a string

Question

For Example; SELECT TRIM(Names) FROM Customer

Answer 1

SELECT LTRIM(RTRIM(Names)) AS Names FROM Customer

Answer 2

To Trim on the right, use:

SELECT RTRIM(Names) FROM Customer

To Trim on the left, use:

SELECT LTRIM(Names) FROM Customer

To Trim on the both sides, use:

SELECT LTRIM(RTRIM(Names)) FROM Customer

Answer 3

I assume this is a one-off data scrubbing exercise. Once done, ensure you add database constraints to prevent bad data in the future e.g.

ALTER TABLE Customer ADD
   CONSTRAINT customer_names__whitespace
      CHECK (
             Names NOT LIKE ' %'
             AND Names NOT LIKE '% '
             AND Names NOT LIKE '%  %'
            );

Also consider disallowing other characters (tab, carriage return, line feed, etc) that may cause problems.

It may also be a good time to split those Names into family_name, first_name, etc :)