sql last name comma first null checks - mysql

Question

I have three columns in the database that represent a person's first, middle, and last names:
People
|------------------------------------------|
| First_Name | Last_name | Middle_name|
|------------------------------------------|
| John | Hansen | T |
| NULL | Smith | NULL |
| Jacob | NULL | J |
| Michael | Johnson | NULL |
|------------------------------------------|
What is the best way to get null safe Last, First Name + Middle Name. So that from the list above I would get:
Hansen, John T
Smith
Jacob J
Johnson, Michael
So far I've got:
select concat_ws(', ', name_last, concat_ws(' ', name_first, name_middle)) as name from entity;
but it's giving me trailing , where I don't want them.

Answer 1

You can use the fact that CONCAT will return NULL if any of the arguments are NULL:
SELECT COALESCE(CONCAT(last_name, ', ', first_name), last_name, first_name)
FROM People
SQL Fiddle Demo
Or, now that you've edited your question to add a Middle_name column:
SELECT COALESCE(CONCAT(last_name, ', ', COALESCE(CONCAT(first_name, ' ', middle_name),first_name,middle_name)),
last_name,
COALESCE(CONCAT(first_name, ' ', middle_name),first_name,middle_name))
FROM People
SQL Fiddle Demo

Answer 2

The other way around:
You have a fullname column containing "firstname middlename lastname"
and want to display it sorted on lastname
Made this as working, at least it works great on dutch names ("van der Boogert" but also single (artist)names.
This example trims the anmes for extra spaces, then counts the amount of spaces in the fullname so no commas are places when its only a single name (artist name)
SELECT
TRIM(fullname) as originalfullname,
length(trim(fullname)) -length(replace(TRIM(fullname), ' ', '')) AS countedzeros,
SUBSTRING_INDEX(TRIM(fullname), ' ', length(TRIM(fullname)) -length(replace(TRIM(fullname), ' ', ''))) AS first_name,
SUBSTRING_INDEX(TRIM(fullname), ' ', -1) AS last_name,
CONCAT(
SUBSTRING_INDEX(TRIM(fullname), ' ', -1),
IF(length(TRIM(fullname)) -length(replace(TRIM(fullname), ' ', '')),', ',''),
SUBSTRING_INDEX(TRIM(fullname), ' ', length(TRIM(fullname)) -length(replace(TRIM(fullname), ' ', '')))
) as dispayname
FROM catalog
group by fullname
/*
Theo van den Boogaart => Boogaart, Theo van den
Hergé => Hergé
Jhonny Smith => Smith, Johnny
*/