I've now got a bunch of structured data in a relational database, and need to get it into Drupal. I've created my content types using CCK. Fortunately, there's a great overview here which highlights some of the core Drupal tables I need to populate which aren't immediately apparent.

Everything is pretty straightforward, apart from populating deltas for repeating fields in CCK.

An example will help here.

Suppose I have a content type of person, who can have multiple phone numbers. CCK lets me add a field of type text, which is defined as a repeating field. To the end user, this looks as though you can simply enter as many phone numbers as you like for this person.

In the database, CCK creates a table called content_type_person, which holds simple fields (i.e. fields where there can only be one value - things like first name, surname). It also creates a separate table for repeating fields, so phone numbers will be stored in content_field_contact_telephone. This new table is keyed on vid and nid (i.e. the current version of the node this person belongs to), and delta. Delta is a zero-based autoincrementing field, which increments for each new value for this nid.

Again, an example will help.

I create a new person, which is internally given nid 1 and vid 1, and added to content-type-person. If I add three phone numbers, these are added to content_field_telephone with nid and vid of 1, and deltas of 0, 1 and 2. A second person with nid 2 would get deltas 0, 1 and 2 again:

nid	vid	delta	phone
1	1	0	01234 567890
1	1	1	01234 567891
1	1	2	01234 567892
2	2	0	01234 567893
2	2	1	01234 567894
2	2	2	01234 567895

I've got hundreds of people, and several phone numbers for each. I can create the content node OK and get the right nid and vid, but how do I then insert all these into the database, and get nice zero-based incrementing delta values?

My previous lives have left me pretty handy with C#. I only really used .net 1.1 for serious heavy lifting, so I'm finding all kinds of nice suprises (like generics - strongly typed ArrayLists at last!) in .net 3.5 now that I've started using Visual Studio 2008 (and finding that the free Express Edition is fine for commercial development came as a rather nice suprise too!).

One of the big down sides with the whole Microsoft ecosystem is the cost of getting off the ground, so as a startup we are going down a pretty standard open source tool route (i.e. LAMP servers). However, we have some fairly sophisticated spidering to be done to get structured data from a fairly large number of web sites of widely varying quality, so in the interests of getting up and running quickly, I've developed the spider in C# (with a fairly massive leg-up from Jeff Heaton - thanks Jeff!). I need to get the spidered data back into MySQL so that our other applications can use it, which brings me to today's problem.