Database Primary Key Naming Conventions

This post specifically deals with the two naming conventions of a primary key for example “Id” or “<tablename>Id".

Using the convention including the tablename prepended to “Id” makes creating and reading SQL query joins more intuitively readable as in:

SELECT a.AuthorId

    , a.AuthorName

    , b.BookId

    , b.BookName 

FROM Author a

   INNER JOIN Book b 

   ON b.AuthorId = a.AuthorId

Versus the alternative using a standard key name, such as “Id" for all tables, as in the following:

SELECT a.Id AS AuthorId

    , a.AuthorName

    , b.Id AS BookId

    , b.BookName 

FROM Author a

   INNER JOIN Book b 

   ON b.AuthorId = a.Id

However it adds additional abstraction/mapping complexity when using a generic Repository pattern* that uses a standard primary key property name for the Repository base classes and interfaces.

*The design is possibly more correctly labeled as a DAO pattern depending on the specific implementation.

photo courtesy: amboo who? / CC BY-SA 2.0

Code-behind Number Format Reference

This post is to save me some time looking up the format reference for some of the things I find myself looking up every once in a while.

Formatting numbers for display like minutes and seconds to have the preceding zero when the number is less than ten (10) as you would see on a digital clock or stopwatch display.

example: [3:07:10]

   1: ' format integers to have preceding zero if 

   2: ' integer is less than 10 (as in a digital

   3: ' clock or stopwatch display)

   4: ' tsElapsed is a TimeSpan

   5: ' lblElapsedTime is a WPF Label

   6: lblElapsedTime.Content = _

   7:     String.Format("{0}:{1}:{2}", _

   8:     tsElapsed.Hours, _

   9:     tsElapsed.Minutes.ToString("0#"), _

  10:     tsElapsed.Seconds.ToString("0#"))