A NULL is a value for which comparison yields neither a true nor false result.NULL = NULL is not true. It’s not false either. The outcome of any comparison of one value to a NULL value is a NULL result.

If you want to check a Column for NULL value then use the following query

Query1

SELECT IFNULL(ColName, '') AS Names
  FROM TableName 

Query2

SELECT CASE WHEN ColName IS NULL
            THEN ''
            ELSE ColName
       END AS TableName 
FROM Test

Query3

 SELECT COALESCE(ColName, 0) as 'ColName' FROM TableName;

Query4

 SELECT IF(ColName IS NULL, '', ColName)
   FROM TableName