CODEWITHSUNDEEP
c#nullablesqldatareader
user1080533
user1080533

Reputation: 865

nullable decimal from SqlDataReader

I use SqlDataReader to read some values from SQL data table. Value is decimal, but it call also be null. How do I assign it? I have tried it like this, but it throws "Specified cast is not valid" exception, if myValue is null. 

decimal? d= (decimal)myRdr["myValue"];

What is the best way to do this?

Thank you.

Upvotes: 1

Views: 4366

Answers (4)

Andy Brown
Andy Brown

Reputation: 19171

decimal? d = myRdr[columnName] as decimal?;

And the above, in an extension method:

public static decimal? GetNullableDecimal(this SqlDataReader myRdr, string columnName, decimal? valueIfNull = null)
{
    return myRdr[columnName] as decimal? ?? valueIfNull;
}

Usage:

decimal? d = myRdr.GetNullableDecimal("myValue");
decimal? d = myRdr.GetNullableDecimal("myValue", valueIfNull: 0);

footnote

Disclaimer. I've only read this, not tested it: "as" casting is said to be 5x faster than prefix (explicit) casting: http://gen5.info/q/2008/06/13/prefix-casting-versus-as-casting-in-c/

Upvotes: 0

dub stylee
dub stylee

Reputation: 3342

This should work:

decimal? d = myRdr["myValue"] == DBNull.Value ? null : decimal.Parse(myRdr["myValue"].ToString());

Upvotes: 1

Selman Genç
Selman Genç

Reputation: 101701

How about this ? 

decimal? d= myRdr["myValue"] == DBNull.Value ? null : (decimal?)myRdr["myValue"];

Upvotes: 3

ekad
ekad

Reputation: 14614

Try this:

decimal? d = myRdr["myValue"] != DBNull.Value ? (decimal)myRdr["myValue"] : null;

Upvotes: 1

Related Questions