Question

I have a table with two fields (countries and ISO codes):

Table1

   field1 - e.g. 'Afghanistan' (without quotes)
   field2 - e.g. 'AF'(without quotes)

In some rows the second field has whitespace at the start and/or end, which is affecting queries.

Table1

   field1 - e.g. 'Afghanistan' (without quotes) 
   field2 - e.g. ' AF' (without quotes but with that space in front)

Is there a way (in SQL) to go through the table and find/replace the whitespace in field2?

Answer 1

You’re looking for TRIM.

UPDATE FOO set FIELD2 = TRIM(FIELD2);

---

Seems like it might be worth it to mention that TRIM can support multiple types of whitespace, but only one at a time and it will use a space by default. You can, however, nest TRIMs.

 TRIM(BOTH ' ' FROM TRIM(BOTH '\n' FROM column))

If you really want to get rid of all the whitespace in one call, you’re better off using REGEXP_REPLACE along with the [[:space:]] notation. Here is an example:

SELECT 
    -- using concat to show that the whitespace is actually removed.
    CONCAT(
         '+', 
         REGEXP_REPLACE(
             '    ha ppy    ', 
             -- This regexp matches 1 or more spaces at the beginning with ^[[:space:]]+
             -- And 1 or more spaces at the end with [[:space:]]+$
             -- By grouping them with `()` and splitting them with the `|`
             -- we match all of the expected values.
             '(^[[:space:]]+|[[:space:]]+$)', 

             -- Replace the above with nothing
             ''
         ), 
         '+') 
    as my_example;
-- outputs +ha ppy+