Validating decimal in C# for storage in SQL Server

Question

I have a decimal database column decimal (26,6).

As far as I can gather this means a precision of 26 and a scale of 6.

I think this means that the number can be a total of 26 digits in length and 6 of these digits can be after the decimal place.

In my WPF / C# frontend I need to validate an incoming decimal so that I can be sure that it can be stored in SQL Server without truncation etc.

So my question is there a way to check that decimal has a particular precision and scale.

Also as an aside I have heard that SQL Server stores decimal in a completely different way to the CLR, is this true and if so is it something I need to worry about?

Answer 1

straight forward way to determine if a given precision,scale of decimal number is greater than 26,6 would be to check the length of its string equivalent.

    public static bool WillItTruncate(double dNumber, int precision, int scale) {
        string[] dString = dNumber.ToString("#.#", CultureInfo.InvariantCulture).Split('.');
        return (dString[0].Length > (precision - scale) || dString.Length>1?dString[1].Length > scale:true);
    }

The maximum precision for C# decimal datatype seems to be 29 digits whereas SQL decimal can have 38 digits. So you may not be hitting the maximum value of SQL decimal from C#.

Answer 2

If you already know destination scale and precision of decimal type at compile time, do simple comparison. For decimal(13,5):

public static bool IsValidDecimal13_5(decimal value)
{
    return -99999999.99999M <= value && value <= 99999999.99999M;
}