Converting DBNull.Value

[João Roberto Alonso]

Hi

I wanto to know if there is a way to convert a DBNull.Value to Decimal and
returns to me Decimal.Zero?

Examples

COLUMN1 = NULL from DB

Ex1.: cstr((dt.rows(0 ).item("COLUMN1 "))

returns Error

Ex2.: dt.rows(0).item ("COLUMN1").toS tring

returns String.Empty

Ex3.: cdec((dt.rows(0 ).item("COLUMN1 "))

returns Error

Is there a way to return to me Decimal.Zero??

I use this...

cdec((iif(dt.ro ws(0).item("COL UMN1") is dbnull.value,
decimal.zero,dt .rows(0).item(" COLUMN1") ) )

[William Ryan]

Re: Converting DBNull.Value

Your way works, the only other way I can think of is using IsNull(Column1,
0) in your SQL Statement, which may or may not be the way to go.

HTH,

Bill
"João Roberto Alonso" <alonsojr@kbone t.com.br> wrote in message
news:udDpQEhfDH A.3024@tk2msftn gp13.phx.gbl...[color=blue]
> Hi
>
> I wanto to know if there is a way to convert a DBNull.Value to Decimal and
> returns to me Decimal.Zero?
>
> Examples
>
> COLUMN1 = NULL from DB
>
> Ex1.: cstr((dt.rows(0 ).item("COLUMN1 "))
>
> returns Error
>
> Ex2.: dt.rows(0).item ("COLUMN1").toS tring
>
> returns String.Empty
>
> Ex3.: cdec((dt.rows(0 ).item("COLUMN1 "))
>
> returns Error
>
> Is there a way to return to me Decimal.Zero??
>
> I use this...
>
> cdec((iif(dt.ro ws(0).item("COL UMN1") is dbnull.value,
> decimal.zero,dt .rows(0).item(" COLUMN1") ) )
>
>
>
>
>
>
>
>[/color]

[Armin Zingler]

Re: Converting DBNull.Value

"João Roberto Alonso" <alonsojr@kbone t.com.br> schrieb[color=blue]
> Hi
>
> I wanto to know if there is a way to convert a DBNull.Value to
> Decimal and returns to me Decimal.Zero?
>
> Examples
>
> COLUMN1 = NULL from DB
>
> Ex1.: cstr((dt.rows(0 ).item("COLUMN1 "))
>
> returns Error
>
> Ex2.: dt.rows(0).item ("COLUMN1").toS tring
>
> returns String.Empty
>
> Ex3.: cdec((dt.rows(0 ).item("COLUMN1 "))
>
> returns Error
>
> Is there a way to return to me Decimal.Zero??
>
> I use this...
>
> cdec((iif(dt.ro ws(0).item("COL UMN1") is dbnull.value,
> decimal.zero,dt .rows(0).item(" COLUMN1") ) )[/color]


If you don't distinguish between Null and zero, why do you allow Null values
in the database at all?

Apart from your current working approach, the only shorter version I can
think of is a function performing the replacement if necessary:

Public Function DecimalNull2Zer o(ByVal Value As Object) As Decimal
If TypeOf Value Is DBNull Then Return 0D
Return DirectCast(Valu e, Decimal)
End Function

Call:
dim d as decimal
d = DecimalNull2Zer o(dt.rows(0).it em("COLUMN1"))

--
Armin

[steve]

Re: Converting DBNull.Value

i don't think there's an option or function in .net that will handle it for
you. you could create your own to handle various types with an option to
return a default value like this psuedo code:

function getDbValue(byva l column as field, byval type as db.datatypes, byval
default as string) as object
on error resume next
if not isnull(column.v alue) return column.value
return ctype(default, type)
end function

*remember the above i *psuedo* code...b4 i get a million flames about the
details.
another route would be to overload the above function, removing the "type"
argument and setting the "default" to int16, int32, long, string, boolean,
etc. for each type of data you need to deal w/...i think the above would
save a lot of proc time when resolving which version vb should use and,
you'd be saving a ton of space in your code project.

the other option, if you have access and aproval, is to handle it w/n the
db.

queries, views, etc. should use:

sql server: isnull(myColumn , dbo.Zero)
oracle: nvl(myColumn, 0)

or in the table def, make the column "DEFAULT 0".

hth,

steve


"João Roberto Alonso" <alonsojr@kbone t.com.br> wrote in message
news:udDpQEhfDH A.3024@tk2msftn gp13.phx.gbl...[color=blue]
> Hi
>
> I wanto to know if there is a way to convert a DBNull.Value to Decimal and
> returns to me Decimal.Zero?
>
> Examples
>
> COLUMN1 = NULL from DB
>
> Ex1.: cstr((dt.rows(0 ).item("COLUMN1 "))
>
> returns Error
>
> Ex2.: dt.rows(0).item ("COLUMN1").toS tring
>
> returns String.Empty
>
> Ex3.: cdec((dt.rows(0 ).item("COLUMN1 "))
>
> returns Error
>
> Is there a way to return to me Decimal.Zero??
>
> I use this...
>
> cdec((iif(dt.ro ws(0).item("COL UMN1") is dbnull.value,
> decimal.zero,dt .rows(0).item(" COLUMN1") ) )
>
>
>
>
>
>
>
>[/color]