two decimal places for decimal/money field

Question

I have a table with money field in my database. I have created entity and created decimal property for that money field. When the value of that field is displayed on My MVC3

Answer 1

The SQL Server money datatype internally is a 64-bit integer with an implied scale of 4 decimal places. To quote Books Online, it is accurate "to ten-thousandsth of a currency unit." It is, the rough equivalent of a decimal(19,4).

The reason for the scale of 4 rather than 2 is to maintain precision in the results of arithmetic. Your ordinary currency value has a scale of 2 (e.g. $3.27) Multiplication or division of two numbers scaled to 2 decimal places gives a results that is precise to 4 decimal places: 9.23 divided by 3.27 yields a result of 2.82262996941896 (approximately). You can carry the result to whatever accuracy (number of decimal places) you desire. However, the result is only precise to 4 decimal places (2.8226) as the original values were only precise to 2 decimal places. That measurement is precise to within 1/2 of the smallest unit specified (+/- 0.005).

But I digress.

As a result of a SQL Server money value having an implied scale of 4, ADO.Net converts the value to a System.Decimal with a scale of 4. And since System.Decimal tracks scale, when you convert it to string, you get 4 decimal places.

To get fewer, you can

• Round it before conversion, using the appropriate Decimal.Round() overload, or
• Format it as desired (eg. (3.27M).ToString("0.00") ;.

Hope this helps.

This program:

namespace Sandbox
{
  using System ;
  class Program
  {
    static void Main( string[] args )
    {
      decimal pi     = (decimal) Math.PI ;
      string  piText = pi.ToString("0.00");
      Console.WriteLine("PI to 2 decimal places is {0} one way, and {1:0.00} another" , piText , pi ) ;
      return;
    }
  }
}

Produces what you'd expect:

PI to 2 decimal places is 3.14 one way, and 3.14 another

Cheers,

N.