Talk:Referential integrity

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Databases (inactive)

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Assumption of reader's knowledge

Quote: "Referential integrity is declared" This is not self-explanatory, unless readers understand what "declared" means. Please link to other articles or explain as appropriate. Apapadop (talk) 10:56, 14 February 2012 (UTC) I added a link to declaration definition for computer science. Not perfect IMHO, but I hope this helps. — Preceding unsigned comment added by Daviburg (talk • contribs) 18:46, 19 March 2012 (UTC)[reply]

Request for clarification

I don't understand the following sentence: "A common problem occurs with relational database tables linked with an 'inner join' which requires non-NULL values in both tables, a requirement that can only be met through careful design and referential integrity." 1) What is the specific 'common problem' that occurs? I also think inner joins with tables having NULL values will be OK as long as the fields joined ON aren't NULL. And field you are joining on is NULL in some row of some table, AFAIK there will be no corresponding output rows. Saying "requires" makes it sound like the entire request would error out or there would be no output at all. I don't see how this is anything but working-as-intended. 2) Why is it that the non-NULL values in both tables requirement can only be met through referential integrity? If for instance one were to do an inner join of the example artist table with the song table as in the example on artist_id, the result set would be reasonable, just not include Aerosmith. Is this the problem? What does it have to do with NULLs? An example where lack of referential integrity leads to NULL values would perhaps help. — Preceding unsigned comment added by 2620:0:1003:1008:9165:F397:300F:2009 (talk) 16:38, 15 June 2015 (UTC)[reply]

I agree, I think whoever wrote that was confused. NULL values are perfectly legal on either side of a foreign key and not returning those rows in query results is the correct behavior of INNER JOIN. I have removed those claims from the article. -- intgr [talk] 07:57, 16 June 2015 (UTC)[reply]

Opinion and not fact

Quote: "This is much more productive (one or two orders of magnitude) than writing custom programming code." This claim does not refer any source. How to verify this content? What does it mean to be more productive by "orders of magnitude"? — Preceding unsigned comment added by Daviburg (talk • contribs) 18:36, 19 March 2012 (UTC)[reply]

It means nothing. Attempts to objectively determine levels of productivity are themselves working on orders of magnitude at best. I would remove it, but this is the kind of sloppy, biased writing that I secretly like on Wikipedia. Whoops, guess I just let the cat out of the bag ;) Psychlohexane (talk) 15:58, 13 April 2012 (UTC)[reply]

EDIT: Also, it's already been removed lololol Psychlohexane (talk) 16:00, 13 April 2012 (UTC)[reply]