Question

I’ve got a tough SQL question for you guys.
I am working with the Webform module of drupal.

How this module works:
– every item on the webform is a new record in the ‘webform_submitted_data’-table,
– sid = registered user
– cid = webform field

Structure of the table:

NID | SID | CID | NO | DATA

1 — 168 — 1 — 0 — XXX

1 — 168 — 2 — 0 — YYY

The problem:
– CID 64 should get updated with the value of CID 56 of the same SID.

Answer 1

I think it should be as follows:

UPDATE webform_submitted_data as a, webform_submitted_data as b 
SET a.data = b.data WHERE a.sid = b.sid AND a.cid = 64 AND b.cid = 56

Basically, you self-join the table (matching SIDs) and then you have both fields in your query, so you can simply refer to each at once.