I want to concatenate two columns in a table with a existing column name using mysql. 

An example: I am having a column `FIRSTNAME` and `LASTNAME` and so many columns also. I want to concatenate these two columns with the name of `FIRSTNAME` only.

So I tried like this:

```
 SELECT *, CONCAT(FIRSTNAME, ',', LASTNAME) AS FIRSTNAME FROM `customer`;

```

but it displaying the two fields with the name of `FIRSTNAME`. one field is having normal values and another one is having concatenated values. I want only one column with those concatenate value. I can select single columns, but am having more than 40 columns in my table.

Is there any way to remove the original column using mysql itself?