删除尾随空格并将其添加为前导空格

Question

I would like to remove the trailing spaces from the expressions in my column and add them to beginning of the expression. So for instance, I currently have the expressions:

Sample_four_space    
Sample_two_space  
Sample_one_space 

I would like to transform this column into:

    Sample_four_space
  Sample_two_space
 Sample_one_space

I have tried this expression:

UPDATE My_Table
SET name = REPLACE(name,'% ',' %')

However, I would like a more robust query that would work for any length of trailing spaces. Can you help me develop a query that will remove all trailing spaces and add them to the beginning of the expression?

Answer 1

If you know all spaces are at the end (as in your example, then you can count them and put them at the beginning:

select concat(space(length(name) - length(replace(name, ' ', ''))),
              replace(name, ' ', '')
             )

Otherwise the better solution is:

select concat(space( length(name) - length(trim(trailing ' ' from name)) ),
              trim(trailing ' ' from name)
             )

or:

select concat(space( length(name) - length(rtrim(name)) ),
              rtrim(name)
             )

Both these cases count the number of spaces (in or at the end of). The space() function then replicates the spaces and concat() puts them at the beginning.