SQL method to replace repeating blanks with single blanks

Is there a more elegant way of doing this. I want to replace repeating blanks with single blanks….

   declare @i int

    set @i=0
    while @i <= 20
    begin
        update myTable
        set myTextColumn = replace(myTextColumn, '  ', ' ')
        set @i=@i+1
    end

(its sql server 2000 – but I would prefer generic SQL)

Answer

Here is a simple set based way that will collapse multiple spaces into a single space by applying three replaces.

DECLARE @myTable TABLE (myTextColumn VARCHAR(50))

INSERT INTO @myTable VALUES ('0Space')
INSERT INTO @myTable VALUES (' 1 Spaces 1 Spaces. ')
INSERT INTO @myTable VALUES ('  2  Spaces  2  Spaces.  ')
INSERT INTO @myTable VALUES ('   3   Spaces  3   Spaces.   ')
INSERT INTO @myTable VALUES ('    4    Spaces  4    Spaces.    ')
INSERT INTO @myTable VALUES ('     5     Spaces  5     Spaces.     ')
INSERT INTO @myTable VALUES ('      6      Spaces  6      Spaces.      ')

select replace(
          replace(
             replace(
                LTrim(RTrim(myTextColumn)), ---Trim the field
             '  ',' |'),                    ---Mark double spaces
          '| ',''),                         ---Delete double spaces offset by 1
       '|','')                              ---Tidy up
       AS SingleSpaceTextColumn
 from @myTable

Your Update statement can now be set based:

 update @myTable
    set myTextColumn = replace(
                          replace(
                             replace(
                                LTrim(RTrim(myTextColumn)),
                             '  ',' |'),
                          '| ',''),
                       '|','')  

Use an appropriate Where clause to limit the Update to only the rows that have you need to update or maybe have double spaces.

Example:

where 1<=Patindex('%  %', myTextColumn)

I have found an external write up on this method: REPLACE Multiple Spaces with One