How to check empty or null in Mysql Query?

If you want to check empty or null value with conditional statement like case when and if in table row with Mysql database. you like to check empty or null value form table then you have multiple way check that. first we check empty value with case when statement then following example.

Empty Check:

SELECT 
   (CASE WHEN COALESCE(email,'')!='' THEN email ELSE 'example@gmail.com' END) as test
FROM `customers`
---------------------OR----------------------
SELECT 
   (CASE COALESCE(email,'') WHEN '' THEN 'example@gmail.com' ELSE email END) as test
FROM `customers`
---------------------OR----------------------
SELECT 
 (IF(COALESCE(email,'')!='',email,'example@gmail.com')) as exp
FROM `customers`
 

Null Check:

SELECT 
  (CASE WHEN email IS NULL THEN 'example@gmail.com' ELSE email END) as test
FROM `customers`
---------------------OR----------------------
SELECT 
  (IF(email IS NULL,'example@gmail.com',email)) as exp
FROM `customers`