问更新维护Null状态的数据库

EN

decimal? dValue; // default value is null
 if(decimalValueExists)
{
  dValue = <value read from text file>
} 

public class MyFields
{
    decimal  req1;
    decimal? opt1; // optional field 1  
}

[WebMethod]
void MyWSMethod(MyFields myFields)
{/* code here will ultimately call InsertMyFields */}

void InsertMyFields(MyFields myFields)
{
    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        // Create the command and set its properties.
        SqlCommand command = new SqlCommand();
        command.Connection = connection;
        command.CommandText = "AddMyFields";
        command.CommandType = CommandType.StoredProcedure;

        // Add the required input parameter
        SqlParameter parameter1 = new SqlParameter();
        parameter1.ParameterName = "@ReqField1";
        parameter1.SqlDbType = SqlDbType.NVarChar;
        parameter1.Direction = ParameterDirection.Input;
        parameter1.Value = myFields.req1;

        // Add the parameter to the Parameters collection. 
        command.Parameters.Add(parameter1);

        // Add the optional parameter and set its properties.
        SqlParameter parameter2 = new SqlParameter();
        parameter2.ParameterName = "@OptField1";
        parameter2.SqlDbType = SqlDbType.NVarChar;
        parameter2.Direction = ParameterDirection.Input;
        parameter2.Value = myFields.opt1 ?? DBNull.Value; //null coalescing operator

        // Add the parameter to the Parameters collection. 
        command.Parameters.Add(parameter2);

        //.. rest of the code
    }

} 

decimal? rebateAmountOrWhatever;

new SqlParameter("@RebateAmount", 
  rebateAmountOrWhatever == null ? (object)DBNull.Value : (object)rebateAmountOrWhatever)

new SqlParameter("@RebateAmount", 
 (object)rebateAmountOrWhatever ?? (object)DBNull.Value)

Nullable<decimal> currentIraBalance = null;