Re: VS2008: How to access properties of a table in O/R designer

  • From: "Ricks Place" <OFBGMail@xxxxxxxxx>
  • To: <programmingblind@xxxxxxxxxxxxx>
  • Date: Thu, 12 Jun 2008 12:46:46 -0400

Man! That looks way diferent than Ado or even regular old Select statements! That problem with the ReadOnly is the one I have run up against. It is the same in DataSet methodology. We are working with PreDefined rows in the schema so any changes must be applied to an instance of the PreDefined row and if we select only 2 columns and tried to update them the other columns would not have any values because they were not a part of the original select statement. Have you found Linq any easier than Ado? It looks verbose. 

Rick USA
----- Original Message ----- From: "Varun Khosla" <varun.lists@xxxxxxxxx> 
To: <programmingblind@xxxxxxxxxxxxx>
Sent: Wednesday, June 11, 2008 12:47 AM
Subject: Re: VS2008: How to access properties of a table in O/R designer



Hi Ricks,
In linq when we query the database like this:
dim resultRow = (from tableVar in dataContext.TableName where
tableVar.key = matchingKeyVar select tableVar).take(1).single()

the resultRow variable is filled up with first row resulting from the
where condition. Now suppose the queried table has 15 columns, and we
want to update the value of column5&6, we can do that like this:
resultRow.column5 = "some value"
resultRow.column6 = "some another value"
And call submit changes like this:
dataContext.SubmitChanges()
It will update those two columns. since resultRow contained values of
all the 15 columns, we don't need to specify the value of each but
only those which we want to update.
But if you had specified a select statement in the linq query like this:
dim resultRow = (from tableVar in dataContext.TableName where
tableVar.key = matchingKeyVar select tableVar.column5,
tableVar.column6).take(1).single()
This query will result in only two columns being members of resultRow,
but as I have seen, these columns are read-only and you cannot change
their value.

HTH

On 6/8/08, Ricks Place <OFBGMail@xxxxxxxxx> wrote:

Hi Guys:
Along these lines:
When I use a DataTable, DataSet, I get Rows on any select. I can limit the data returned to a couple of columns but it seems I have to provide values 
for an entire row or the values are messed up during an update. I don't
think I can just set and update a couple of columns using the DataSet Update 
function. Is this the case with Linq? Can you just Select a couple of
columns, set them and then apply an update for them or will that tip other 
columns in the original row?
I hope I explained this well enough to understand and my understanding is
correct. I had problems like this some time ago so always just read entire rows, update whatever columns I want then ReWrite the entire row. This is, 
of course, pretty inefficient and I even had to write a TableAdapter
extension to avoid Optimistic Concurrency for a particular update since it 
was so blasted slow and unnessisary for the particular update.
Anyway, while on the Linq topic I thought I would ask in case someone has
had experience with this situation.
Rick Farmington Mich. USA
If you knowal Message -----
From: "Varun Khosla" <varun.lists@xxxxxxxxx>
To: <programmingblind@xxxxxxxxxxxxx>
Sent: Sunday, June 08, 2008 3:10 AM
Subject: Re: VS2008: How to access properties of a table in O/R designer



By the way, I've found an alternative for this. Locate the table in
the designer window, press shortcut key, open add sub-menu, click
property - it will take you to the list of the columns for that table
focussing an edit box forcing you to specify a name for the new
property. Pressing the shift+tab creates a new property with the
default name property1, since it's not required one can delete it by
selecting it in the listbox and pressing the dell key.

I know that this is not the right way to go about it, but this is the
only way I'm able to know to go about it. (smile)


On 6/7/08, Varun Khosla <varun.lists@xxxxxxxxx> wrote:

P.P.S. is additional postscript

On 6/1/08, Chris Hallsworth <christopherhallsworth71@xxxxxxxxxxxxxx>
wrote:

Hi what's PPS? I've heard of PS but not PPS? Thanks and sorry for my
ignorance.
--
Chris Hallsworth
  ----- Original Message -----
  From: Varun Khosla
  To: programmingblind@xxxxxxxxxxxxx
  Sent: Monday, June 02, 2008 8:13 AM
  Subject: VS2008: How to access properties of a table in O/R designer


  Hello listers,
  Has anybody worked on VS2008? It has new feature called LINQ
(Language-Integrated Query) designed to further increased the
speed/object
orientation of working with database. It has added an O/R designer for
this
purpose. User can drag-drop tables from server explorer to the designer 
to
create a data context which is the focle point of LINQ.
Dragging/dropping
part is okay because Jaws has a shortcut key for this purpose. The
problem
I'm facing is how to access properties of the table object (don't
confuse
properties here with the general properties of any components such as
Name
which can be accessed via f4 in O/R as well, but with the properties
here
I
mean by columns of a table) so that I can delete specific columns that I 
don't require (only from the table class of O/R designer and not from
the
database).

  Has anybody gotten an idea as to how it can be done?

  P.S. I've not been able to find a shortcut key for this anywhere on
the
net.
P.P.S. Sighted folks can access it with the mouse, but there's no text 
written at that point to make jaws cursor do the job.

  Thanks

  --
  Varun



--
Varun




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Varun
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