Is a MySQL statement from an external script possible?

Question

I'm working with a PM on a Drupal project, and we're having little success finding a developer to answer (what we believe to be) a simple question. I'm afraid I have no Drupal experience to speak of.

We've made well aware that Drupal itself doesn't use MySQL statements per se, but it is MySQL based, so - is it possible to write a SQL statement to find all users that have purchased a particular product/sku? The SQL is to be used in an external script, outside of the website itself.

The developer is vague, at best, so I can't be any more specific than the fact that it's Drupal 7 using a standard ecommerce package. I absolutely hate asking a broad question like this, but we're locked into this particular resource, and is insisting it will take 100+ hours to get this data to us, and I am unable to get to the DB to even try to construct the SQL.

Any advice is appreciated! (and if you want some contract work, I'd be MORE than happy to talk).

Clarification

Again, I know this is vague, and the SQL itself would be a bonus in the answer. The challenge is that the developer insists that Drupal doesn't use SQL statements, and therefore an external script isn't possible because it will take 100 hours to write a Drupal module to get that the result of the query. I'm imagining something like this to determine if/when a customer last ordered product #1234.:

SELECT MAX(o.orderdate) 
FROM users AS u
JOIN orders AS o on o.userid = u.userid
JOIN orderitems AS i on i.orderid = o.orderid
JOIN products AS p on o.productid = i.productid
WHERE u.email = 'somecustomer@example.com' AND o.productid=1234

With my limited Drupal experience, I know that this example isn't close to correct, but in principal, this is what we need to execute on a different server, with different software to simply get a date or a null. If she'd give us credentials to look at the database, I could probably figure it out, but her "position" in the matter is that it can only be done with this exhaustive module development effort that she seems to want to do.

Answer 1

Drupal does use SQL statements to communicate with the database, however it does so through a built in abstraction layer. That said, you can write regular old SQL from any PHP script to query the information you need, as long as you have the database connection info. Personally I would build whatever functionality you're after into a custom Drupal module, and then use that to interface with whichever external service you're working with. We would need a bit more information on exactly what you're trying to achieve to provide more specific feedback however.

Answer 2

Yes it's absolutely possible, but almost certainly not the best way to do things.

Drupal uses MySQL (or equivalent) to store data, so it has to use SQL statements to store data. This is done at the core level (meaning the vast majority of developers will never need to write SQL statements for their Drupal development). Instead, developers call various Drupal functions that will run the appropriate SQL statements. Basically you can think of it like this: as a developer, you tell Drupal you want to save a certain object type and it will translate your object into SQL statements that save it in the database the best way it knows how.

Drupal saves data in dozens of tables. A user might have their information saved in half a dozen tables, and your products could be saved in many more. To find the history purchases of users via SQL statements is probably more difficult than hiring a developer to write a custom module that would be able to calculate that for you and potentially even track and display purchase trends going forward in a much cleaner way. As far as the 100 hour estimate, I'm not sure.. I'm betting that some e-commerce modules already store this historical purchase information and they could probably be setup in an hour or so. Others might not have that functionality and will need some custom code that could take 100 hours, sure.

Instead of insisting on running SQL statements to run your reports, find out which modules your e-commerce store is using (perhaps ubercart?). Then do some research to find out of that module already offers the functionality you're looking for (or ask your developer to do that research). If not, a custom module might be required, otherwise other modules (like the rules module) could be sufficient.

I highly recommend you do not run external SQL scripts. If you do, I highly recommend you do not hire a Drupal developer to do it and instead hire a Database Administrator (which is probably much more expensive than a Drupal developer). Instead, you should hire a Drupal developer with the following experience:

1. Has developed a Drupal module (more than just hello world)
2. Has experience with the e-commerce module your Drupal site uses
3. Understands what MVC is and how Drupal implements MVC
4. Has at least 3 years of PHP experience

That developer will be able to tell you the best way forward for your case.