Question

I have huge tables (3 millions records) that must have a joined column. This value will not change.

How can I add a column based on a join? There will be some other queries. If I use join, it will be a slower process.

Ex:

Main Table:

add_cod | name
 1      | alfa
 2      | beta
 1      | zeta

Addon Table:

cod | col_ext
 1  | jam
 2  | bam

The result should be the main table, but with col_ext column:

add_cod | name | col_ext
 1      | alfa |   jam
 2      | beta |   bam
 1      | zeta |   jam

Answer 1

This is a simple JOIN.

SELECT  a.*, b.col_ext
FROM    main a
        INNER JOIN addon b
            ON a.add_cod = b.cod

You don’t have to worry about performance if you have properly implemented index on your tables.

SQLFiddle Demo