"tom c" <tomca***@gmail.com> wrote in message
news:1157513300.751253.306230@i42g2000cwa.googlegroups.com...
>I create 2 data OleDbDataAdapters, one with the wizard, and one in
> code.  I know the adapter created in code is OK because I use it to
> fill a data table.
>
> However, when I try to use the same SQL insert statement in the two
> adapters, the adapter created with the wizard works fine, but the
> adapter created in code gives me an error "Object reference not set to
> an instance of an object".  The code is below.  What am I doing wrong?
>
> 'OleDbDataAdapter1 is created by the wizard.  daA is created in code.
>
> sqlA = "Select ID1, ID2 from CrossRef"
> Dim daA As OleDbDataAdapter = New OleDbDataAdapter(sqlA, ConnA)
> OleDbDataAdapter1.InsertCommand.CommandText = SQL 'this works fine
> daA.InsertCommand.CommandText = SQL 'this gives an error
>
> What am I missing?
>

> if you look in the designer, and click on the daA, expand the InsertCommand
> property and i'll bet it is empty.  you can choose the correct OleDbCommand
> object from the menu.  then you won't get a NULLreferenceException when you
> access daA.InsertCommand.CommandText.
>
> it should be clear from the Exception that the InsertCommand property of the
> daA object is set to Null, so when you try and access the CommandText
> property of a null object, you get the exception.
> a good idea in this case is to debug the code and when the exception
> happens, examine the object in question.  you'll see in the debugger
> <undefined> (i think) next to any null properties.
>
> hope this helps
> tim
>
>
> "tom c" <tomca***@gmail.com> wrote in message
> news:1157513300.751253.306230@i42g2000cwa.googlegroups.com...
> >I create 2 data OleDbDataAdapters, one with the wizard, and one in
> > code.  I know the adapter created in code is OK because I use it to
> > fill a data table.
> >
> > However, when I try to use the same SQL insert statement in the two
> > adapters, the adapter created with the wizard works fine, but the
> > adapter created in code gives me an error "Object reference not set to
> > an instance of an object".  The code is below.  What am I doing wrong?
> >
> > 'OleDbDataAdapter1 is created by the wizard.  daA is created in code.
> >
> > sqlA = "Select ID1, ID2 from CrossRef"
> > Dim daA As OleDbDataAdapter = New OleDbDataAdapter(sqlA, ConnA)
> > OleDbDataAdapter1.InsertCommand.CommandText = SQL 'this works fine
> > daA.InsertCommand.CommandText = SQL 'this gives an error
> >
> > What am I missing?
> >

"tom c" <tomca***@gmail.com> wrote in message
news:1157552634.605426.76570@i3g2000cwc.googlegroups.com...
> Thanks so much Tim.
>
> You are correct.  I used the debugger, set a break point, right clicked
> daA, did a "Quick Watch", and I could see that insertcommand is set to
> nothing.
> I didn't know you could do that.
>
> What I still don't understand is how I cerate the insert command.
>
> How do I do that?  What was left out of my original code that is needed
> to create the insert, update and delete commands?
>
> Tom
>
>
> Tim_Mac wrote:
>> if you look in the designer, and click on the daA, expand the
>> InsertCommand
>> property and i'll bet it is empty.  you can choose the correct
>> OleDbCommand
>> object from the menu.  then you won't get a NULLreferenceException when
>> you
>> access daA.InsertCommand.CommandText.
>>
>> it should be clear from the Exception that the InsertCommand property of
>> the
>> daA object is set to Null, so when you try and access the CommandText
>> property of a null object, you get the exception.
>> a good idea in this case is to debug the code and when the exception
>> happens, examine the object in question.  you'll see in the debugger
>> <undefined> (i think) next to any null properties.
>>
>> hope this helps
>> tim
>>
>>
>> "tom c" <tomca***@gmail.com> wrote in message
>> news:1157513300.751253.306230@i42g2000cwa.googlegroups.com...
>> >I create 2 data OleDbDataAdapters, one with the wizard, and one in
>> > code.  I know the adapter created in code is OK because I use it to
>> > fill a data table.
>> >
>> > However, when I try to use the same SQL insert statement in the two
>> > adapters, the adapter created with the wizard works fine, but the
>> > adapter created in code gives me an error "Object reference not set to
>> > an instance of an object".  The code is below.  What am I doing wrong?
>> >
>> > 'OleDbDataAdapter1 is created by the wizard.  daA is created in code.
>> >
>> > sqlA = "Select ID1, ID2 from CrossRef"
>> > Dim daA As OleDbDataAdapter = New OleDbDataAdapter(sqlA, ConnA)
>> > OleDbDataAdapter1.InsertCommand.CommandText = SQL 'this works fine
>> > daA.InsertCommand.CommandText = SQL 'this gives an error
>> >
>> > What am I missing?
>> >
>

> hi tom,
> no problem.  debugging is a truly essential skill for a developer, i'm glad
> you got it going.  whenever anything goes wrong in your code now, you can
> jump right in with the debugger and identify the problem point quickly.
>
> usually what happens with the dataAdapters is you configure them in the VS
> designer.  if you choose the SQL statement option, then it will
> automatically generate OleDbCommand objects for Update,Delete,Insert and
> Select, and attach them correctly to the DataAdapter.
> if you choose Stored Procedures then you have to instruct VS which sproc
> should be used for each of the 4 commands.  if you leave out any of the 4
> command types, then there will be no OleDbCommand object for that function
> type (Insert/Update etc).
>
> if you then look in the code behind, you will see 4 OleDbCommand objects
> called OleDbSelectCommand1, OleDbInsertCommand1 etc.
>
> you can re-configure the dataadapter by right-clicking it in the VS
> designer.
> alternatively you can expand the InsertCommand property of the dataAdapter
> in the VS designer and choose 'new' from the menu.  then you can set up the
> command as you like, setting the connection, commandText properties etc.
>
> does that make sense?
> tim
>
>
>
>
> "tom c" <tomca***@gmail.com> wrote in message
> news:1157552634.605426.76570@i3g2000cwc.googlegroups.com...
> > Thanks so much Tim.
> >
> > You are correct.  I used the debugger, set a break point, right clicked
> > daA, did a "Quick Watch", and I could see that insertcommand is set to
> > nothing.
> > I didn't know you could do that.
> >
> > What I still don't understand is how I cerate the insert command.
> >
> > How do I do that?  What was left out of my original code that is needed
> > to create the insert, update and delete commands?
> >
> > Tom
> >
> >
> > Tim_Mac wrote:
> >> if you look in the designer, and click on the daA, expand the
> >> InsertCommand
> >> property and i'll bet it is empty.  you can choose the correct
> >> OleDbCommand
> >> object from the menu.  then you won't get a NULLreferenceException when
> >> you
> >> access daA.InsertCommand.CommandText.
> >>
> >> it should be clear from the Exception that the InsertCommand property of
> >> the
> >> daA object is set to Null, so when you try and access the CommandText
> >> property of a null object, you get the exception.
> >> a good idea in this case is to debug the code and when the exception
> >> happens, examine the object in question.  you'll see in the debugger
> >> <undefined> (i think) next to any null properties.
> >>
> >> hope this helps
> >> tim
> >>
> >>
> >> "tom c" <tomca***@gmail.com> wrote in message
> >> news:1157513300.751253.306230@i42g2000cwa.googlegroups.com...
> >> >I create 2 data OleDbDataAdapters, one with the wizard, and one in
> >> > code.  I know the adapter created in code is OK because I use it to
> >> > fill a data table.
> >> >
> >> > However, when I try to use the same SQL insert statement in the two
> >> > adapters, the adapter created with the wizard works fine, but the
> >> > adapter created in code gives me an error "Object reference not set to
> >> > an instance of an object".  The code is below.  What am I doing wrong?
> >> >
> >> > 'OleDbDataAdapter1 is created by the wizard.  daA is created in code.
> >> >
> >> > sqlA = "Select ID1, ID2 from CrossRef"
> >> > Dim daA As OleDbDataAdapter = New OleDbDataAdapter(sqlA, ConnA)
> >> > OleDbDataAdapter1.InsertCommand.CommandText = SQL 'this works fine
> >> > daA.InsertCommand.CommandText = SQL 'this gives an error
> >> >
> >> > What am I missing?
> >> >
> >

"tom c" <tomca***@gmail.com> wrote in message
news:1157559322.929422.287470@d34g2000cwd.googlegroups.com...
>I have a lot to learn.
>
> When you create the dataadapter with the designer,  how do you see the
> code in  code behind?  I am using Visual Web Developer 2005 Express
> edition.
>
> When you say:
>> usually what happens with the dataAdapters is you configure them in the
>> VS
>> designer.
>
> do you mean the  wizard that comes up when you drag the dataadaper
> control on to the form?
>
> I thought that is gave you more control to actually write the code
> instead of using the wizard, but maybe that is old fashioned.
>
> Thanks again
> Tom
>
>
> Tim_Mac wrote:
>> hi tom,
>> no problem.  debugging is a truly essential skill for a developer, i'm
>> glad
>> you got it going.  whenever anything goes wrong in your code now, you can
>> jump right in with the debugger and identify the problem point quickly.
>>
>> usually what happens with the dataAdapters is you configure them in the
>> VS
>> designer.  if you choose the SQL statement option, then it will
>> automatically generate OleDbCommand objects for Update,Delete,Insert and
>> Select, and attach them correctly to the DataAdapter.
>> if you choose Stored Procedures then you have to instruct VS which sproc
>> should be used for each of the 4 commands.  if you leave out any of the 4
>> command types, then there will be no OleDbCommand object for that
>> function
>> type (Insert/Update etc).
>>
>> if you then look in the code behind, you will see 4 OleDbCommand objects
>> called OleDbSelectCommand1, OleDbInsertCommand1 etc.
>>
>> you can re-configure the dataadapter by right-clicking it in the VS
>> designer.
>> alternatively you can expand the InsertCommand property of the
>> dataAdapter
>> in the VS designer and choose 'new' from the menu.  then you can set up
>> the
>> command as you like, setting the connection, commandText properties etc.
>>
>> does that make sense?
>> tim
>>
>>
>>
>>
>> "tom c" <tomca***@gmail.com> wrote in message
>> news:1157552634.605426.76570@i3g2000cwc.googlegroups.com...
>> > Thanks so much Tim.
>> >
>> > You are correct.  I used the debugger, set a break point, right clicked
>> > daA, did a "Quick Watch", and I could see that insertcommand is set to
>> > nothing.
>> > I didn't know you could do that.
>> >
>> > What I still don't understand is how I cerate the insert command.
>> >
>> > How do I do that?  What was left out of my original code that is needed
>> > to create the insert, update and delete commands?
>> >
>> > Tom
>> >
>> >
>> > Tim_Mac wrote:
>> >> if you look in the designer, and click on the daA, expand the
>> >> InsertCommand
>> >> property and i'll bet it is empty.  you can choose the correct
>> >> OleDbCommand
>> >> object from the menu.  then you won't get a NULLreferenceException
>> >> when
>> >> you
>> >> access daA.InsertCommand.CommandText.
>> >>
>> >> it should be clear from the Exception that the InsertCommand property
>> >> of
>> >> the
>> >> daA object is set to Null, so when you try and access the CommandText
>> >> property of a null object, you get the exception.
>> >> a good idea in this case is to debug the code and when the exception
>> >> happens, examine the object in question.  you'll see in the debugger
>> >> <undefined> (i think) next to any null properties.
>> >>
>> >> hope this helps
>> >> tim
>> >>
>> >>
>> >> "tom c" <tomca***@gmail.com> wrote in message
>> >> news:1157513300.751253.306230@i42g2000cwa.googlegroups.com...
>> >> >I create 2 data OleDbDataAdapters, one with the wizard, and one in
>> >> > code.  I know the adapter created in code is OK because I use it to
>> >> > fill a data table.
>> >> >
>> >> > However, when I try to use the same SQL insert statement in the two
>> >> > adapters, the adapter created with the wizard works fine, but the
>> >> > adapter created in code gives me an error "Object reference not set
>> >> > to
>> >> > an instance of an object".  The code is below.  What am I doing
>> >> > wrong?
>> >> >
>> >> > 'OleDbDataAdapter1 is created by the wizard.  daA is created in
>> >> > code.
>> >> >
>> >> > sqlA = "Select ID1, ID2 from CrossRef"
>> >> > Dim daA As OleDbDataAdapter = New OleDbDataAdapter(sqlA, ConnA)
>> >> > OleDbDataAdapter1.InsertCommand.CommandText = SQL 'this works fine
>> >> > daA.InsertCommand.CommandText = SQL 'this gives an error
>> >> >
>> >> > What am I missing?
>> >> >
>> >
>

> hi tom,
> i'm not too familiar with the Visual Web Developer, but i would say the
> wizard is close enough to what i was describing.  Visual Studio also has a
> wizard to configure the dataadapter.
>
> you can certainly configure the DataAdapter in your code, and i wouldn't say
> it's old-fashioned by any means. it's just that you need to know more about
> what goes on 'under the hood' if you do want to hand-write the code.  the
> wizard will create all the objects it needs, and set all the properties that
> need to be set, and create proper typed parameters for all the commands.  if
> you do it by hand, then you need to know how to do all these things
> yourself.
>
> As a brief example: OleDbDataAdapter is a class.  it has a property called
> InsertCommand of type OleDbCommand.  unless you set an OleDbCommand object
> for this property then you can't use it! (because it is null).  all
> properties are null unless something is assigned to them (either by you in
> your code, or the property may be initialised by the class itself).
>
> personally i'd recommend using the wizard because it is easier to update
> later on if you change your database.  then you can just re-run the wizard,
> instead of having to trawl through 100 lines of code and manually identify
> the parameters that have changed for your Select, Insert, Delete and Update
> commands.  it's always nice to move higher up the food chain so to speak, by
> writing less code, but as you rightly point out, it is good to know what is
> happening underneath.
>
> hope this helps
> tim
>
>
>
>
>
>
> "tom c" <tomca***@gmail.com> wrote in message
> news:1157559322.929422.287470@d34g2000cwd.googlegroups.com...
> >I have a lot to learn.
> >
> > When you create the dataadapter with the designer,  how do you see the
> > code in  code behind?  I am using Visual Web Developer 2005 Express
> > edition.
> >
> > When you say:
> >> usually what happens with the dataAdapters is you configure them in the
> >> VS
> >> designer.
> >
> > do you mean the  wizard that comes up when you drag the dataadaper
> > control on to the form?
> >
> > I thought that is gave you more control to actually write the code
> > instead of using the wizard, but maybe that is old fashioned.
> >
> > Thanks again
> > Tom
> >
> >
> > Tim_Mac wrote:
> >> hi tom,
> >> no problem.  debugging is a truly essential skill for a developer, i'm
> >> glad
> >> you got it going.  whenever anything goes wrong in your code now, you can
> >> jump right in with the debugger and identify the problem point quickly.
> >>
> >> usually what happens with the dataAdapters is you configure them in the
> >> VS
> >> designer.  if you choose the SQL statement option, then it will
> >> automatically generate OleDbCommand objects for Update,Delete,Insert and
> >> Select, and attach them correctly to the DataAdapter.
> >> if you choose Stored Procedures then you have to instruct VS which sproc
> >> should be used for each of the 4 commands.  if you leave out any of the 4
> >> command types, then there will be no OleDbCommand object for that
> >> function
> >> type (Insert/Update etc).
> >>
> >> if you then look in the code behind, you will see 4 OleDbCommand objects
> >> called OleDbSelectCommand1, OleDbInsertCommand1 etc.
> >>
> >> you can re-configure the dataadapter by right-clicking it in the VS
> >> designer.
> >> alternatively you can expand the InsertCommand property of the
> >> dataAdapter
> >> in the VS designer and choose 'new' from the menu.  then you can set up
> >> the
> >> command as you like, setting the connection, commandText properties etc.
> >>
> >> does that make sense?
> >> tim
> >>
> >>
> >>
> >>
> >> "tom c" <tomca***@gmail.com> wrote in message
> >> news:1157552634.605426.76570@i3g2000cwc.googlegroups.com...
> >> > Thanks so much Tim.
> >> >
> >> > You are correct.  I used the debugger, set a break point, right clicked
> >> > daA, did a "Quick Watch", and I could see that insertcommand is set to
> >> > nothing.
> >> > I didn't know you could do that.
> >> >
> >> > What I still don't understand is how I cerate the insert command.
> >> >
> >> > How do I do that?  What was left out of my original code that is needed
> >> > to create the insert, update and delete commands?
> >> >
> >> > Tom
> >> >
> >> >
> >> > Tim_Mac wrote:
> >> >> if you look in the designer, and click on the daA, expand the
> >> >> InsertCommand
> >> >> property and i'll bet it is empty.  you can choose the correct
> >> >> OleDbCommand
> >> >> object from the menu.  then you won't get a NULLreferenceException
> >> >> when
> >> >> you
> >> >> access daA.InsertCommand.CommandText.
> >> >>
> >> >> it should be clear from the Exception that the InsertCommand property
> >> >> of
> >> >> the
> >> >> daA object is set to Null, so when you try and access the CommandText
> >> >> property of a null object, you get the exception.
> >> >> a good idea in this case is to debug the code and when the exception
> >> >> happens, examine the object in question.  you'll see in the debugger
> >> >> <undefined> (i think) next to any null properties.
> >> >>
> >> >> hope this helps
> >> >> tim
> >> >>
> >> >>
> >> >> "tom c" <tomca***@gmail.com> wrote in message
> >> >> news:1157513300.751253.306230@i42g2000cwa.googlegroups.com...
> >> >> >I create 2 data OleDbDataAdapters, one with the wizard, and one in
> >> >> > code.  I know the adapter created in code is OK because I use it to
> >> >> > fill a data table.
> >> >> >
> >> >> > However, when I try to use the same SQL insert statement in the two
> >> >> > adapters, the adapter created with the wizard works fine, but the
> >> >> > adapter created in code gives me an error "Object reference not set
> >> >> > to
> >> >> > an instance of an object".  The code is below.  What am I doing
> >> >> > wrong?
> >> >> >
> >> >> > 'OleDbDataAdapter1 is created by the wizard.  daA is created in
> >> >> > code.
> >> >> >
> >> >> > sqlA = "Select ID1, ID2 from CrossRef"
> >> >> > Dim daA As OleDbDataAdapter = New OleDbDataAdapter(sqlA, ConnA)
> >> >> > OleDbDataAdapter1.InsertCommand.CommandText = SQL 'this works fine
> >> >> > daA.InsertCommand.CommandText = SQL 'this gives an error
> >> >> >
> >> >> > What am I missing?
> >> >> >
> >> >
> >