sql - MySQL combine two columns and add into a new column

Question

I have the following structure with a MySQL table:

+----------------+----------------+----------+
|    zipcode     |      city      |   state  |
+----------------+----------------+----------+
|     10954      |     Nanuet     |    NY    |
+----------------+----------------+----------+

I want to combine the above 3 columns into one column like this:

+---------------------+
|      combined       |
+---------------------+
| 10954 - Nanuet, NY  |
+---------------------+

And I want to add this "combined" column to the end of the table without destroying the original 3 fields.

Answer 1

Create the column:

ALTER TABLE yourtable ADD COLUMN combined VARCHAR(50);

Update the current values:

UPDATE yourtable SET combined = CONCAT(zipcode, ' - ', city, ', ', state);

Update all future values automatically:

CREATE TRIGGER insert_trigger
BEFORE INSERT ON yourtable
FOR EACH ROW
SET new.combined = CONCAT(new.zipcode, ' - ', new.city, ', ', new.state);

CREATE TRIGGER update_trigger
BEFORE UPDATE ON yourtable
FOR EACH ROW
SET new.combined = CONCAT(new.zipcode, ' - ', new.city, ', ', new.state);