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

User · Answer

SELECT CONCAT  zipcode    -    city        state  AS COMBINED FROM TABLE

User · Answer

Are you sure you want to do this  In essence  you re duplicating the data that is in the three original columns  From that point on  you ll need to make sure that the data in the combined field matches the data in the first three columns  This is more overhead for your application  and other processes that update the system will need to understand the relationship   If you need the data  why not select in when you need it  The SQL for selecting what would be in that field would be   SELECT CONCAT zipcode    -    city        state  FROM Table    This way  if the data in the fields changes  you don t have to update your combined field

User · Answer

Add new column to your table and perfrom the query   UPDATE tbl SET combined   CONCAT zipcode    -    city        state

User · Answer

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

[mysql] MySQL combine two columns and add into a new column

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