Ask about DBNULL to other types

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hi am asking about my error see my screen shot, thanks

DBNULL to other types I create my c# code to read a excel file but something had a problem see above my screen shot

other problem , I inputted your code but will shown an error see screenshot below

The column (at index 8) in the row you're reading from is null. You can't store null in a decimal. — Rob, Feb 09 '17 at 06:15

score 0 · Answer 1 · answered Feb 09 '17 at 06:18

I don't know what database library you're using, but most libraries built on-top of ADO.NET do not always use a .NET null reference to indicate a SQL NULL value. That's what DBNull is for (accessed via DBNull.Value). You can test for SQL NULL by using the Object Reference Equality operator == or Object.ReferenceEquals.

Your code is rather convoluted. I suggest you try this instead:

Object value = row[8]; // I don't know what `row` is, change this to be a more specific type if there are any type-safety constraints on `row[8]`.
if( Object.ReferenceEquals( DBNull.Value, value ) ) {
    // value is SQL NULL
}
else {
    // value is not SQL NULL, but it is not necessarily a Decimal value either

    if( value is Decimal ) {

        return (Decimal)value; // you can't use the shorthand `as` operator with value-types like Decimal
    }
}

sujith karivelil · Answer 2 · 2017-02-09T06:21:29.960

0

Hope that there may be a chance for row[8] to be DBNull. in such cases you can check that by comparing row[8] with System.DBNull.Value.
try like this:

if (row[8] != System.DBNull.Value))
{
   decimal quantity; 
   if(decimal.TryParse(row[8].ToString(), out quantity)
   {
      item.ONHANDQTY = quantity;
   } 
}

edited Feb 09 '17 at 06:21

answered Feb 09 '17 at 06:19

sujith karivelil

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This is inefficient if `row[8]` is already a `Decimal` value instead of a string. – Dai Feb 09 '17 at 06:20
@Dai: yep you are correct in that sense. But I have considered `Convert.ToDecimal` in the OP's code – sujith karivelil Feb 09 '17 at 06:23

score -2 · Answer 3 · edited Feb 09 '17 at 12:34

-2

use or (||) condition instead of and (&&) condition, as shown below:

if(onhand == "" || row[8] == System.DBNULL.value)
{
    //your code
}
else
{
    ONHANDQTY=Convert.toDecimal(row[8]);
}

edited Feb 09 '17 at 12:34

Am_I_Helpful

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answered Feb 09 '17 at 06:17

kritikaTalwar

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`DBNull` and `null` are not the same. – Rob Feb 09 '17 at 06:18
okay sir , I try this thnaks – J.Cloud Feb 09 '17 at 06:18

Ask about DBNULL to other types

3 Answers3