Question

Is there any way to shorten/easier read the following SQL to concatenate a string.

SELECT
   CONCAT(       
    IF(location_address1 != '',
       CONCAT(location_address1, ", "),
       ""
    ),
    IF(location_address2 != '',
       CONCAT(location_address2, ", "),
       ""
    ),
    IF(location_town != '',
       CONCAT(location_town, ", "),
       ""
    ),
    IF(location_region != '',
       CONCAT(location_region, ", "),
       ""
    ),
    IF(location_postcode != '',
       CONCAT(location_postcode, ", "),
       ""
    ),
    c.country_name
   )      
FROM
   countries c      
WHERE
   c.country_id = locations.country_id LIMIT 1

Answer 1

CONCAT_WS() does not skip empty strings. However, it does skip any NULL values after the separator argument.

NULLIF(expr1,expr2)
Returns NULL if expr1 = expr2 is true, otherwise returns expr1.

SO your query could be:

SELECT 
  CONCAT_WS(', ', 
       NULLIF(location_address1, ''),
       NULLIF(location_address2, ''),
       NULLIF(location_town, ''), 
       NULLIF(location_region, ''), 
       NULLIF(location_postcode, ''), 
       NULLIF(country_name, '')
  ) AS address
FROM
   countries c      
WHERE
   c.country_id = locations.country_id LIMIT 1