how to concat two columns into one with the existing column name in mysql?

Question

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

Answer 1

Remove the * from your query and use individual column names, like this:

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

Using * means, in your results you want all the columns of the table. In your case * will also include FIRSTNAME. You are then concatenating some columns and using alias of FIRSTNAME. This creates 2 columns with same name.