mysql concat删除结尾的破折号（如果存在）

Question

I have a select that concats several columns together separating them with a dash "-" character. The last column 'description' may or may not have a value. If it does, all is good, if it doesn't, I end up with a "-" at the end. How can I get rid of the last character only if it is a "-"?

SELECT CONCAT(locationid,'-',city,'-',state,'-',country,'-',description) FROM sys_locations ORDER BY locationid

Example with 'description' column populated: AUC01-Aurora-CO-US-DC

Example with 'description' column empty: AUM01-Auburn Hills-MI-US- <- notice trailing dash.

Thanks, David

Answer 1

You need NULLIF :

SELECT CONCAT_WS('-', locationid, city, state, country, NULLIF(description, '')) 
FROM sys_locations ORDER BY locationid

Answer 2

你可以这样

SELECT CONCAT(locationid,'-',city,'-',state,'-',country,IF(description is null,'',concat('-', description))) FROM sys_locations ORDER BY locationid

Answer 3

To handle both NULL and '', try this:

SELECT CONCAT(locationid,'-', city, '-', state, '-', country, case when description IS NULL or description = '' then '' else '-' end, description)
FROM sys_locations ORDER BY locationid