how to inherit mysql tables - mysql

Question

I have 30 tables in a database, all InnoDB. They have their structure.
What I want to do is actually adding the bellow columns to EVERY table.
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` text COLLATE utf8_unicode_ci NOT NULL,
`description` text COLLATE utf8_unicode_ci NOT NULL,
`categoryId` int(11) NOT NULL,
`imageId` int(11) NOT NULL,
`created` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`updated` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`createdId` int(11) NOT NULL,
`updatedId` int(11) NOT NULL,
`allowedEmployeeIds` text COLLATE utf8_unicode_ci NOT NULL,
In a programming language (assume PHP) the normal approach is to create an abstract class, put all of the common variables there, and then inherit from it. What about MySQL? how should I do this?
For reasons coming from design, it's not possible for me to create a commonData table and use foreign keys / join. Please note that I am writing the create statements from scratch, so there is no need for update.

Answer 1

I'd think through this for a while -- it's complicated and will add a lit to what you're trying to do. It'll add a lot of work later.
But if you really want to do this, the way to do it is not to put this in the table definition, but to create a script that can add these columns to a table.
Something like:
ALTER TABLE table_name
ADD `id` int(11) NOT NULL AUTO_INCREMENT,
ADD `name` text COLLATE utf8_unicode_ci NOT NULL,
ADD `description` text COLLATE utf8_unicode_ci NOT NULL,
ADD `categoryId` int(11) NOT NULL,
ADD `imageId` int(11) NOT NULL,
ADD `created` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
ADD `updated` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
ADD `createdId` int(11) NOT NULL,
ADD `updatedId` int(11) NOT NULL,
ADD `allowedEmployeeIds` text COLLATE utf8_unicode_ci NOT NULL;
Then simply execute this script for each table you have.
If you want to write a script to do this flor all tables, use the command:
SHOW TABLES;
to find all the tables. Then loop through all the tables and execute the alter script on all the tables.

Answer 2

I think the most practical way to do this would be to use a GUI mysql interface to duplicate the tables. For example, on mac you could use SequelPro and duplicate the table as needed, which would only take a few seconds, rather than writing the CREATE TABLEs in a shell script or otherwise.

Answer 3

Mysql has no concept of table inheritance. You will need to add all those columns to every table. I would write a script to generate the MODIFY TABLE ... ADD ... statements for every table you care about, then run the result against your database.
I'm skeptical you can't find some other way to organize your data that doesn't require adding the same exact columns to 30 tables.

Answer 4

I know this is an old topic, but the solutions presented show how to create the required columns at table creation time - really a typing-saving device.
I was thinking about this more from a point of design. In this case, a second table could be defined with the common columns. For example :
CREATE TABLE article
:
:
CREATE TABLE classified_ad
:
:
CREATE TABLE details
:
`details_id` int(11) NOT NULL AUTO_INCREMENT,
`name` text COLLATE utf8_unicode_ci NOT NULL,
`description` text COLLATE utf8_unicode_ci NOT NULL,
:
`categoryId` int(11) NOT NULL,
`allowedEmployeeIds` text COLLATE utf8_unicode_ci NOT NULL,
parent_id int(11) NOT NULL
parent_table enum('classified_ad', 'article')
The one issue with this would be the performance hit from forcing a join. So therefore there probably won't be much benefit to these schema.
However, if you need to report across the details. For example report on employees allowed, then this will see benefits, for example
SELECT * from details WHERE allowedEmployeeIds = '1';
compared to say, a union when doing it with separate tables.