SQL using If Not Null on a Concatenation

Question

If I have the table

SELECT (Firstname || \'-\' || Middlename || \'-\' || Surname)  AS example_column
FROM example_table

This will

Answer 1

This approach works:

select first_name || coalesce('-' || middle_name, '') || '-' || last_name 
from t;

Output:

|        ?column? |
|-----------------|
|      john-smith |
| jane-anne-smith |

UPDATE

Live code: http://sqlfiddle.com/#!15/d5a1f/1

Just as my inkling, someone will give a scenario that is not in the question. So to make it work with empty middle name. Just add a nullif for empty string:

select first_name || coalesce('-' || nullif(middle_name,'') , '') || '-' || last_name 
from t;

Output:

|        ?column? |
|-----------------|
|      john-smith |
|      obi-kinobi |
| jane-anne-smith |