Maintaining Cross-Database Referential Integrity

It is often convenient to house your master tables in a separate database from application specific databases so that primary keys are copasetic and multiple databases have access to the same lookups.

Common examples would include employees, counties, regions and other lookup tables.

Once these tables are in a separate database however it is no longer possible to simply drag-and-drop a relationship between them to maintain referential integrity.

Here's a Solution
For this example we'll use an Observation table, tied to a master list of Sex, that's right, Sex (we could call it Gender to be all PC, but these are animals, not Pat in the Personnel Department.)

Step 1:
We create a new view called PIC_Sex in our Application Database by querying the table PIC_Sex in our Master Database:

CREATE VIEW dbo.PIC_Sex AS
SELECT SexID, Sex, Rank
FROM Master.dbo.PIC_Sex
ORDER BY Rank

Yes, that's right, Male and Female! Slugs are awesome.

Step 2:
We create a new user-defined function xdf_ValidateSex to validate if a given SexID exists in the view PIC_Sex.

CREATE FUNCTION [dbo].[xdf_ValidateSex] (
@SexID int
)
RETURNS int AS
BEGIN
RETURN
(
SELECT SexID FROM [dbo].[PIC_Sex] WHERE SexID = @SexID
)
END

You could make this function accept table names to make it more reusable.

Step 3:
In our Observation Table we add a constraint on the field SexID which tests against the function xdf_ValidateSex to see if the SexID exists.

Enter the following Constraint Expression:

([dbo].[xdf_ValidateSex]([SexID]) is not null)

Viola! You can now validate Sex programmatically!

Comments

Attachment Reminder - and more for MS Outlook

I just did it again. We don't like to admit it, but we all have. You write a long letter describing the attachment, press send and then 10 seconds later remember you didn't actually attach the message. I finally decided to do something about it. Turns out it isn't too hard. Chiefly because Jimmy Peña at Code for Excel and Outlook already did all the hard work of writing up an excellent MS Outlook Etiquette Check Macro that does all the dirty work for you. What's left for you to do? In MS Outlook go to Tools > Macros > Visual Basic Editor Under the Project Panel (far left) Browse to Project1 > Microsoft Office Outlook Objects > ThisOutlookSession Double-click ThisOutlookSesson to Open (if you haven't been here before this will be a big blank canvas) Visit Code for Excel and Outlook Etiquette Check Code and select "Copy to Clipboard" at the top of the code. Or you can also copy from the code I've modified below if you prefer....

Simple HTTP Redirect with Querystring in IIS7

HTTP Redirect seems simple enough. Always was in IIS6 and in IIS7 there's even a button labeled HTTP Redirect that promises relative redirects. It looks like it'll be as easy Apache finally. That is until you try to redirect a querystring. Then everything bombs. Turns out it still is relatively easy, except you have to know that Microsoft changed $S$Q to $V$Q. Why? $Ss and $Gs I suspect. And How. In our example we'll redirect all pages under http://olddomain.com/content to http://mydomain.com/content. Pick the virtual directory you want to redirect. e.g. http://olddomain.com/content Click HTTP Redirect under IIS in the IIS management console. In the HTTP Redirect Dialog: Check Redirect requests to this destination Enter your new path ending with $V$Q. e.g. http://mydomain.com$V$Q Counter-intuitively check Redirect all request to exact destination (instead of relative destination) Choose the appropriate Status Code (Permanent or Temp...

ArcGIS One-to-Many Labeling

ArcGIS is just plain lousy at dealing with any relationship that isn't one-to-one. We all have a slew of hacks just to deal with this limitation. I for one regularly am creating temporary cross-tab queries so I can represent multiple sample results at a collection point, fish surveyed at a cross-section and a host of other relationships. The classic example for mapping comes from the cadastral community and condominium lots. It's an odd situation where more than one person has title to the same piece of ground. How do you represent this? I've got a new trick thanks to Mohammed Hoque's article in ArcUser Magazine. We're going to do a database query inside a label expression, loop through the results and output the entire list to label. For our example we'll use Outfitting Areas in Idaho and we'll label them with the Outfitters and Guide License Numbers and Outfitter Names. 1.) Open ArcGIS and add your spatial layer with the unique identifier shared with...

oneidía

Search This Blog