help with dataset current position....

[hemenkap]

hi friends,

 

i have been programming with dataset since 2 weeks, well i do know that dataset does not support a cursor like the recordset so we cannot get the current position in the recordset.

 

however i have created an user control for handling the navigation of the dataset as well as to handle saving of form data plus othe functions also.

 

in that control i am passing the dataset as well as the table name in the dataset to navigate and the navigation works just fine.

 

i am even able to retrive my current position in the dataset using my control ( however this works only if you are navigating thru the database using the navigation buttons provided).

 

now waht i am trying to do is that when the user enters some data in a field on the form. on each key press event i check if the

textbox.TEXT matches with any of the rows in a particular column in the database.

 

if NO MATCH means that the user may be entering a new record and form enters INSERT MODE, if there is a match the all the remaing textboxes are filled to diaplay the data for that recoed and the form enters EDIT MODE.

 

however when this happens what i want to do is that i want to update my navigation control so that it displays my current position in the dataset..

 

i am locatin the current row using the

dataset.tables.Select method as i am not searchin on primary key.

 

my navigation control uses

 

me.parentform.bindingcontext(dataset.tables).posotion to locate my current position in the dataset....

 

 

if onyl you can tell me that once i do a Select/Find using the textbox.Text string AND if i hit a row ( it will always return one row only as the string is unique ) how to know the position of this row. As both these method return a row/ or row collection. but i am not intrested much in the row returned. it is the position that is outmost important...

 

if any body can help it will be truly great

 

thanks.

Hemen

[Nerseus]

You have two options. Loop through the DataSet one row at a time (using a "for i =..." type of loop) and compare the value manually. When (and if) a match is found, you have your row number.

 

The other method uses a DataView. You can use the DataView's Find method (similar to Select) but returns a row index.

 

-Nerseus

[hemenkap]

ok thanks,

 

i dont think looping is a good option as there could be more than 5000 records and looping is tedious.

i will try the dataviews find method and see if this works.

 

will surely tell if it worked or now.

thanks once againg for help...

 

Hemen Kapadia

[hemenkap]

Hi Nerseus,

 

thanks for replying.

i tried it out.

but did not help....

can you think of any other way.....

 

Hemen

[jc3]

Hi

 

To find current record, you must use BindingManagerBase object

(

More information about )

 

For example:

'ds1 - DataSet

'Example - name of the DataSet's table

'idRow - name of the keycolumn

 

Dim bm As BindingManagerBase

bm = Me.BindingContext.Item(ds1, "Example")

 

Dim dr As DataRowView = CType(bm.Current, DataRowView) 'you must cast Current object to corret type

 

MessageBox.Show(CType(dr.Item("idRow"), String))

 

--

I was writing this example without VS Editor.

Get a reply how it working

 

PS. Sorry for grammar - my english is very poor :(

 

jc3

[hemenkap]

thanks,

 

but dr.Item("IDRow") will return the data stored in the

colum called idRow in the database. it dont want that . it want the position of the datarow in the dataset.

 

what i need is this, i am explaining it in terms of recordset.

as it might make things clear.

 

when we do recordset.Find ( SOME CRITERIA )

the the recordset is searched for all rows and it stops at the row which satisfies our condition.

moves to current row pointer to that row.

 

now since in a dataset there is nothing like the current row pointer ( this is the reason we do not have anything like Move last, move first etc...) . i treied a lot will try this too.

if it works i will let you know

 

bye,

hemen Kapadia

[joyin]

I too am stuck with the same problem in Vb.net.

 

Can someone please guide as to how one can get the position of a datarow in a dataset?

 

Any help will be greatly appreciated.:confused:

Edited May 12, 2003 by joyin

[hemenkap]

hi friends,

 

finally after about 2 months this problem is solved.

you can do the following as i do it.

 

the commandtext of my select command looks like this.

 

SELECT * FROM TABLE

ORDER BY COLUMN_YOU_WANT_TO_SEARCH_ON

 

the column on which i order is the customer code ( for example)

which i have ket unique and is indexed as i dont want to repeat codes

the primary key is and integer column hidden from the user of the system.

 

now once you have filled a table in the dataset you have to create a dataview from this table using the ORDER BY column to sort it.

 

The dataview.Find method returns an index ( long ) of the position of the current datarow in the sorted dataset rather than

the actual datarow as returned by most other find methods.

 

this is the only way i could do it. if anybody knows any better way do let me know.

 

i dont remember the actual dataview code. it is very small about 3 to 4 lines you can see it in MSDN

 

Hemen Kapadia