data-integrity

We are currently developing an application in which multiple entities have associated opening hours. Opening hours may span multiple days, or may be contained within a single day. Ex. Opens Monday at 6:00 and closes at Friday at 18:00. Or Opens Monday at 06:00 and closes Monday at 15:00. Also, an entity may have multiple sets of opening hours per day. So far, the best design I have found, is to define an opening hour to consist of the following: StartDay, StartTime, EndDay and EndTime. This design allows for all the needed flexibility. However, data integrity becomes an issue. I cannot seem to

I have seen a feature in different web applications including Wordpress (not sure?) that warns a user if he/she opens an article/post/page/whatever from the database, while someone else is editing the same data simultaneously. I would like to implement the same feature in my own application and I have given this a bit of thought. Is the following example a good practice on how to do this? It goes a little something like this: 1) User A enters a the editing page for the mysterious article X. The database table Events is queried to make sure that no one else is editing the same page for the

Trying to determine how quickly a user would be warned of corruption in the object database with git-1.7.4.1, I pulled a one-bit switcheroo: $ git init repo Initialized empty Git repository in /tmp/repo/.git/ $ cd repo $ echo 'very important info' >critical $ git add critical $ git commit -m critical [master (root-commit) c4d6d90] critical 1 files changed, 1 insertions(+), 0 deletions(-) create mode 100644 critical $ git ls-tree HEAD 100644 blob 82d423c32c4bb2c52938088e0234db041bf4eaaf critical $ git show 82d423c32c4bb2c52938088e0234db041bf4eaaf very important info $ echo 'Very important info'

It appears that the lack of support for enforcing 2 basic constraints (unique and foreign key), is a reason for loss of many man-hours debugging and troubleshooting difficult problems. What starts as a trivial, easy-to-fix problem (dup rows /inconsistent primary-detail tables) goes un-noticed, grows and raises complex edge-scenarios in our application, or even in our hardware (e.g. self-join with dups can cause inflation and storage exhaustion). Netezza serves multiple purposes in our environment: production, research, qa and staging. Naturally our ETL processes can’t be mature and can’t

This question already has an answer here: Can a foreign key be NULL and/or duplicate? 11 answers In our database project we have a table Sale that has an primary key and two exclusive foreign keys: Vehicle_ID and Piece_ID . For example if we sell a vehicle we need Vehicle_ID as a foreign key but not Piece_ID . Can we put NULL to Piece_ID , could a foreign key be null? Or is there a way to do this job? Thanks. The column (or columns) of a primary key must be NOT NULL. A record cannot be uniquely identified by a NULL. So the ID columns on the referenced end of the foreign key must be defined as