MySQL Select Column if Not Null only

Question

I have this mysql code:

SELECT firstname, lastname, age, gender from persons WHERE id = 1;

Display:

> firstname: Marlon 
> 
> lastname: Null
> 
> age: 26
> 
> gender: male

What I want to do is:

SELECT IF NULL DONT SELECT(firstname), IF NULL DONT SELECT(lastname), IF NULL DONT SELECT(age), IF NULL DONT SELECT(gender) from persons WHERE id = 1;

Display:

> firstname: Marlon 
> 
> age: 26
> 
> gender: male

lastname didn't display because its null

Answer 1

Certainly you can't do that; rather you can use COALESCE() or IFNULL() function to provide a default value in case of NULL like

SELECT firstname, 
COALESCE(lastname,'N/A'),
age,
gender from persons WHERE id = 1;

(OR) if you want to remove that record completely then use a WHERE condition like

SELECT firstname, lastname, age, gender from persons 
WHERE id = 1 AND lastname IS NOT NULL;

Answer 2

even there is no way to hide column but yes you can avoid null value in output. So there can be below 2 ways-

Method 1: You can keep field blank where it is null.

SELECT IFNULL(firstname,'') AS firstname, 
IFNULL(lastname,'') AS lastname, 
IFNULL(age,'') AS age, 
IFNULL(gender,'') AS gender 
FROM persons WHERE id = 1;

Method2: You can get all values in single column using concatenate function.

SELECT CONCAT
(
IFNULL(firstname,''),' ',
 IFNULL(lastname,''),' ', 
IFNULL(age,''),' ', 
IFNULL(gender,'')
) 
FROM persons WHERE id = 1;