Hello
Could you please help for a simple boolean expression
If a is not equal to Null
I tried
If (a != null) Then
This expression does not work
I look at Help but can not find out
Could you please help
Thanks
S.Hoa
9  4155 
> Could you please help for a simple boolean expression If a is not equal to Null
I tried
If (a != null) Then
From my point of view it seems that you are trying
to check whether object exists.
Try:
If Not (a Is Nothing) Then
--
Pozdrav,
Josip Medved, MCSD http://www.jmedved.com
What sort of "Null" are you looking for?
Database Null?
Object is Nothing?
a <> 0&?
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098135675 .785296@ftpsrv1 ... Hello
Could you please help for a simple boolean expression
If a is not equal to Null
I tried
If (a != null) Then
This expression does not work
I look at Help but can not find out
Could you please help
Thanks
S.Hoa
Thank you
a is a value of a field in a table of a database. I have to check it is null
or not
I have a solution
If Not (a is DBNull.Value) Then
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:OI******** ******@TK2MSFTN GP09.phx.gbl... What sort of "Null" are you looking for?
Database Null?
Object is Nothing?
a <> 0&?
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098135675 .785296@ftpsrv1 ... Hello
Could you please help for a simple boolean expression
If a is not equal to Null
I tried
If (a != null) Then
This expression does not work
I look at Help but can not find out
Could you please help
Thanks
S.Hoa
you got it, mostly.
i'm not certain if the IS keyword will give you the proper results or not.
this is not a value comparison, but an Object Reference comparison.
it would be safer to use:
If Not (a = DBNull.Value) Then
or use the alternate test using
If Not IsDBNull(a) Then
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098141920 .570486@ftpsrv1 ... Thank you
a is a value of a field in a table of a database. I have to check it is
null or not
I have a solution
If Not (a is DBNull.Value) Then
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:OI******** ******@TK2MSFTN GP09.phx.gbl... What sort of "Null" are you looking for?
Database Null?
Object is Nothing?
a <> 0&?
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098135675 .785296@ftpsrv1 ... Hello
Could you please help for a simple boolean expression
If a is not equal to Null
I tried
If (a != null) Then
This expression does not work
I look at Help but can not find out
Could you please help
Thanks
S.Hoa
Thank you
I tried to use =, the compiler get the error
Operator '=' is not defined for types 'System.Object' and 'System.DBNull' .
Use 'Is' operator to compare two reference types.
Therefore, I have to change to "Is"
I use VB.Net 2001
Regards
S.Hoa
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:eP******** ******@TK2MSFTN GP10.phx.gbl... you got it, mostly.
i'm not certain if the IS keyword will give you the proper results or not.
this is not a value comparison, but an Object Reference comparison.
it would be safer to use:
If Not (a = DBNull.Value) Then
or use the alternate test using
If Not IsDBNull(a) Then
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098141920 .570486@ftpsrv1 ... Thank you
a is a value of a field in a table of a database. I have to check it is
null or not
I have a solution
If Not (a is DBNull.Value) Then
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:OI******** ******@TK2MSFTN GP09.phx.gbl... What sort of "Null" are you looking for?
Database Null?
Object is Nothing?
a <> 0&?
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098135675 .785296@ftpsrv1 ...
> Hello
>
> Could you please help for a simple boolean expression
>
> If a is not equal to Null
>
> I tried
>
> If (a != null) Then
>
> This expression does not work
>
> I look at Help but can not find out
>
> Could you please help
>
> Thanks
> S.Hoa
>
>
What object type is "a"?
You say a database field, but which object.
Is there an a.value property?
I'm still concerned about using IS here.
Take for example that A is a particular object, and System.DBNull is another
object.
The IS operator is more appropriate to determine if "A" is the same object
as DBNull, not the same value.
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098147081 .668852@ftpsrv1 ... Thank you
I tried to use =, the compiler get the error
Operator '=' is not defined for types 'System.Object' and 'System.DBNull' .
Use 'Is' operator to compare two reference types.
Therefore, I have to change to "Is"
I use VB.Net 2001
Regards
S.Hoa
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:eP******** ******@TK2MSFTN GP10.phx.gbl... you got it, mostly.
i'm not certain if the IS keyword will give you the proper results or
not. this is not a value comparison, but an Object Reference comparison.
it would be safer to use:
If Not (a = DBNull.Value) Then
or use the alternate test using
If Not IsDBNull(a) Then
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098141920 .570486@ftpsrv1 ... Thank you
a is a value of a field in a table of a database. I have to check it
is null or not
I have a solution
If Not (a is DBNull.Value) Then
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in
message news:OI******** ******@TK2MSFTN GP09.phx.gbl...
> What sort of "Null" are you looking for?
> Database Null?
> Object is Nothing?
> a <> 0&?
>
> "HS1" <so*@slingshot. co.nz> wrote in message
> news:1098135675 .785296@ftpsrv1 ...
> > Hello
> >
> > Could you please help for a simple boolean expression
> >
> > If a is not equal to Null
> >
> > I tried
> >
> > If (a != null) Then
> >
> > This expression does not work
> >
> > I look at Help but can not find out
> >
> > Could you please help
> >
> > Thanks
> > S.Hoa
> >
> >
>
>
Here is my code
If (DataGrid1.Item (DataGrid1.Curr entCell.RowNumb er, 5) Is DBNull.Value) Then
In this code, dataGrid1 presents data for a table. I check the value
(textual type) of current row at column 5 to see that it is Null or not.
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:u2******** ******@tk2msftn gp13.phx.gbl... What object type is "a"?
You say a database field, but which object.
Is there an a.value property?
I'm still concerned about using IS here.
Take for example that A is a particular object, and System.DBNull is
another object.
The IS operator is more appropriate to determine if "A" is the same object
as DBNull, not the same value.
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098147081 .668852@ftpsrv1 ... Thank you
I tried to use =, the compiler get the error
Operator '=' is not defined for types 'System.Object' and
'System.DBNull' . Use 'Is' operator to compare two reference types.
Therefore, I have to change to "Is"
I use VB.Net 2001
Regards
S.Hoa
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:eP******** ******@TK2MSFTN GP10.phx.gbl... you got it, mostly.
i'm not certain if the IS keyword will give you the proper results or
not. this is not a value comparison, but an Object Reference comparison.
it would be safer to use:
If Not (a = DBNull.Value) Then
or use the alternate test using
If Not IsDBNull(a) Then
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098141920 .570486@ftpsrv1 ...
> Thank you
> a is a value of a field in a table of a database. I have to check it is null
> or not
> I have a solution
>
> If Not (a is DBNull.Value) Then
>
> "Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message > news:OI******** ******@TK2MSFTN GP09.phx.gbl...
> > What sort of "Null" are you looking for?
> > Database Null?
> > Object is Nothing?
> > a <> 0&?
> >
> > "HS1" <so*@slingshot. co.nz> wrote in message
> > news:1098135675 .785296@ftpsrv1 ...
> > > Hello
> > >
> > > Could you please help for a simple boolean expression
> > >
> > > If a is not equal to Null
> > >
> > > I tried
> > >
> > > If (a != null) Then
> > >
> > > This expression does not work
> > >
> > > I look at Help but can not find out
> > >
> > > Could you please help
> > >
> > > Thanks
> > > S.Hoa
> > >
> > >
> >
> >
>
>
Ah, I see. Well, if it were me, I would explicitly cast the underlying value
to its appropriate sqltype then check for null. However, I do not know what
kind of underlying data you are dealing with.
You could take the shortcut and use the Convert.IsDBNul l which will handle
an expression.
Like so:
If Convert.IsDBNul l(DataGrid1.Ite m(DataGrid1.Cur rentCell.RowNum ber, 5)) Then
It is possible that the way you are doing it will work fine. But it just
seems dangerous to me.
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098163724 .554694@ftpsrv1 ... Here is my code
If (DataGrid1.Item (DataGrid1.Curr entCell.RowNumb er, 5) Is DBNull.Value)
Then
In this code, dataGrid1 presents data for a table. I check the value
(textual type) of current row at column 5 to see that it is Null or not.
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:u2******** ******@tk2msftn gp13.phx.gbl... What object type is "a"?
You say a database field, but which object.
Is there an a.value property?
I'm still concerned about using IS here.
Take for example that A is a particular object, and System.DBNull is
another object.
The IS operator is more appropriate to determine if "A" is the same
object as DBNull, not the same value.
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098147081 .668852@ftpsrv1 ... Thank you
I tried to use =, the compiler get the error
Operator '=' is not defined for types 'System.Object' and 'System.DBNull' . Use 'Is' operator to compare two reference types.
Therefore, I have to change to "Is"
I use VB.Net 2001
Regards
S.Hoa
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in
message news:eP******** ******@TK2MSFTN GP10.phx.gbl...
> you got it, mostly.
> i'm not certain if the IS keyword will give you the proper results
or not. > this is not a value comparison, but an Object Reference comparison.
> it would be safer to use:
> If Not (a = DBNull.Value) Then
>
> or use the alternate test using
> If Not IsDBNull(a) Then
>
> Gerald
>
> "HS1" <so*@slingshot. co.nz> wrote in message
> news:1098141920 .570486@ftpsrv1 ...
> > Thank you
> > a is a value of a field in a table of a database. I have to check
it is > null
> > or not
> > I have a solution
> >
> > If Not (a is DBNull.Value) Then
> >
> > "Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in
message > > news:OI******** ******@TK2MSFTN GP09.phx.gbl...
> > > What sort of "Null" are you looking for?
> > > Database Null?
> > > Object is Nothing?
> > > a <> 0&?
> > >
> > > "HS1" <so*@slingshot. co.nz> wrote in message
> > > news:1098135675 .785296@ftpsrv1 ...
> > > > Hello
> > > >
> > > > Could you please help for a simple boolean expression
> > > >
> > > > If a is not equal to Null
> > > >
> > > > I tried
> > > >
> > > > If (a != null) Then
> > > >
> > > > This expression does not work
> > > >
> > > > I look at Help but can not find out
> > > >
> > > > Could you please help
> > > >
> > > > Thanks
> > > > S.Hoa
> > > >
> > > >
> > >
> > >
> >
> >
>
>
Thank you
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:eD******** ******@TK2MSFTN GP14.phx.gbl... Ah, I see. Well, if it were me, I would explicitly cast the underlying
value to its appropriate sqltype then check for null. However, I do not know
what kind of underlying data you are dealing with.
You could take the shortcut and use the Convert.IsDBNul l which will handle
an expression.
Like so:
If Convert.IsDBNul l(DataGrid1.Ite m(DataGrid1.Cur rentCell.RowNum ber, 5))
Then
It is possible that the way you are doing it will work fine. But it just
seems dangerous to me.
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098163724 .554694@ftpsrv1 ... Here is my code
If (DataGrid1.Item (DataGrid1.Curr entCell.RowNumb er, 5) Is DBNull.Value) Then
In this code, dataGrid1 presents data for a table. I check the value
(textual type) of current row at column 5 to see that it is Null or not.
"Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message
news:u2******** ******@tk2msftn gp13.phx.gbl... What object type is "a"?
You say a database field, but which object.
Is there an a.value property?
I'm still concerned about using IS here.
Take for example that A is a particular object, and System.DBNull is
another object.
The IS operator is more appropriate to determine if "A" is the same object as DBNull, not the same value.
Gerald
"HS1" <so*@slingshot. co.nz> wrote in message
news:1098147081 .668852@ftpsrv1 ...
> Thank you
>
> I tried to use =, the compiler get the error
>
> Operator '=' is not defined for types 'System.Object' and
'System.DBNull' . > Use 'Is' operator to compare two reference types.
> Therefore, I have to change to "Is"
> I use VB.Net 2001
>
> Regards
> S.Hoa
> "Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in message > news:eP******** ******@TK2MSFTN GP10.phx.gbl...
> > you got it, mostly.
> > i'm not certain if the IS keyword will give you the proper results or not.
> > this is not a value comparison, but an Object Reference
comparison. > > it would be safer to use:
> > If Not (a = DBNull.Value) Then
> >
> > or use the alternate test using
> > If Not IsDBNull(a) Then
> >
> > Gerald
> >
> > "HS1" <so*@slingshot. co.nz> wrote in message
> > news:1098141920 .570486@ftpsrv1 ...
> > > Thank you
> > > a is a value of a field in a table of a database. I have to
check it is
> > null
> > > or not
> > > I have a solution
> > >
> > > If Not (a is DBNull.Value) Then
> > >
> > > "Gerald Hernandez" <Cablewizard@sp *********@Yahoo .com> wrote in
message
> > > news:OI******** ******@TK2MSFTN GP09.phx.gbl...
> > > > What sort of "Null" are you looking for?
> > > > Database Null?
> > > > Object is Nothing?
> > > > a <> 0&?
> > > >
> > > > "HS1" <so*@slingshot. co.nz> wrote in message
> > > > news:1098135675 .785296@ftpsrv1 ...
> > > > > Hello
> > > > >
> > > > > Could you please help for a simple boolean expression
> > > > >
> > > > > If a is not equal to Null
> > > > >
> > > > > I tried
> > > > >
> > > > > If (a != null) Then
> > > > >
> > > > > This expression does not work
> > > > >
> > > > > I look at Help but can not find out
> > > > >
> > > > > Could you please help
> > > > >
> > > > > Thanks
> > > > > S.Hoa
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>
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