Close, Open, Update, UpdateBatch, AbsolutePosition, and more

David Smith

Can someone give me logic in c sharp that's equivalent to the Close, Open, Update, UpdateBatch, AbsolutePosition, Find, Delete, MoveFirst, MoveNext, MoveLast, in visual basic 6.0 using a disconnected dataset (Datatable)?

Close (Not supported)

Closes a Recordset

Delete (Not supported)
Deletes a record or a group of records

Open (Not supported)
Opens a database element that gives you access to records in a table, the results of a query, or to a saved Recordset

Find(Not supported)
Searches for a record in a Recordset that satisfies a specified criteria

MoveFirst(Not supported)
Moves the record pointer to the first record

MoveNext(Not supported)
Moves the record pointer to the next record

MoveLast(Not supported)
Moves the record pointer to the Last record

Update (Not supported)
Saves all changes made to a single record in a Recordset object

UpdateBatch (Not supported)
Saves all changes in a Recordset to the database. Used when working in batch update mode

AbsolutePosition (Not supported)
Sets or returns a value that specifies the ordinal position of the current record in the Recordset object

7 Replies

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Vulpes12y ago
With an ADO RecordSet, the Open method specifies what you want to load from the database. This includes a whole table, the results of a SQL query or a stored procedure. You call the Close method when you've finished working with the RecordSet to release the resources it's using.

Normally, the connection to the database server is maintained whilst you're working with a RecordSet.

With ADO.NET, you open a connection to the database server as you would with ADO.

However, you then create a command object which contains your SQL query or a reference to a stored procedure and (typically) associate it with a DataAdapter.

When you call the DataAdapter's Fill method, this fills a DataSet with the results of the query and you can then close the connection to the server.

So the DataSet and the DataTables it contains are completely disconnected from the underlying data source and act to all intents and purposes like any other .NET collection except that they have infrastructure built-in which tracks changes so that these can easily be written back to the database using the DataAdapter's Update method.

Consequently DataTables neither have, nor need, Open and Close methods and can be used as soon as they've been populated. When you no longer need them you can set the variable to null to facilitate garbage collection.

Nor do they have an Update command as this is dealt with by the DataAdapter which writes the updates, whether there be one or many, to the database in an efficent matter though you can set the batch size using its UpdateBatchSize method.

As I said in my previous post, there is no concept of a current row in a DataTable. You can pull out any row from the table at any time simply by using its index. So, if AbsolutePosition has any counterpart at all, it's just the index of the row that you're working on at the time (+1, as it's '1' based in ADO).

If I may say so, I think you're faced here with an almost impossible task to give equivalents between ADO and ADO.NET since, despite the similar name, they're completely different technologies. Your programmers really need to have a good grasp of the principles of both ADO and ADO.NET so they can produce code which achieves the same thing rather than attempting a rigid translation between the two.
David Smith12y ago
Vuples,

Responding to your comment below

"Once it's been created and populated it remains in memory until there are no longer any references to it when it's automatically marked for garbage collection in the same way as any other object."

So are you saying there no other way to close or open a datatable in c sharp, similiar how it was done in visual basic 6.0, if so, can you add logic on the thread. I am documenting at the moment. We are upgrading from vb6 to c sharp on one of the projects. I am basically make a document that saids if you see this in the visual basic 6 code, do this in c sharp if that make sense. Leading them in a direction.

Also what about the commands below,

Update (Not supported)
Saves all changes made to a single record in a Recordset object

UpdateBatch (Not supported)
Saves all changes in a Recordset to the database. Used when working in batch update mode

AbsolutePosition (Not supported)
Sets or returns a value that specifies the ordinal position of the current record in the Recordset object
Vulpes12y ago
As a DataTable is disconnected from the underlying database, there's no concept of opening or closing it like there is with an ADO Recordset.

Once it's been created and populated it remains in memory until there are no longer any references to it when it's automatically marked for garbage collection in the same way as any other object.

Similarly, there's no concept of a current record.

However, suppose you have a DataTable, dt, let's say.

If you're navigating through dt's rows and you're looking at record 'i' (where 0 <= i < dt.Rows.Count), then:

the current row is:

DataRow currentRow = dt.Rows[i];

The next row can be found like this:

DataRow nextRow = null;
if (i < dt.Rows.Count - 1) nextRow = dt.Rows[++i];

The previous row like this:

DataRow prevRow = null;
if (i > 0) prevRow = dt.Rows[--i];

The first row like this:

DataRow firstRow = null;
if(dt.Rows.Count > 0) firstRow = dt.Rows[0];

and the last row like this:

DataRow lastRow = null;
if(dt.Rows.Count > 0) lastRow = dt.Rows[dt.Rows.Count - 1];

If you're looking at the 'i'th row of the DataTable, then the nearest thing to the Recordset's AbsolutePosition property would be (i + 1) as that is '1' based rather than '0' based.

To delete the row at index 'i' in the DataTable, you can do:

dt.Rows.RemoveAt(i);

To find a row, whilst there is a dt.Rows.Find() method which can find a row which has a specific primary key, there's also the more powerful dt.Select() method which can find all records which satisfy a 'filter expression'.There is a special syntax for writing these expressions.

As far as updating is concerned, whilst you can call the dt.AcceptChanges method to commit all changes made to the DataTable since the last time the method was called, to actually write those changes to the underlying database you'd normally use the DbDataAdapter object (and its Update method in particular) that was used to populate the DataTable in the first place.

This object will then generate the appropriate SQL INSERT, DELETE or UPDATE commands to write the changes back to the database.
David Smith12y ago
We are using windows form, we are not doing any coding right now. We are eventually migrating all code from vb6 to c sharp winforms. With the properties mention above, I just want to know c sharp equivalent logic using a datatable. Vb6 uses recordsets. We are migrating to datatsbles.

For example.

If I see recordset close property in vb6, what is the logic equivalent for a datatable in c sharp. Datatablr does not have a close property
Riddhi Valecha12y ago
Hi..

You can load the records in GridView and use paging.

Refer-

http://www.aspsnippets.com/Articles/Paging-in-ASPNet-GridView-Example.aspx
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http://www.c-sharpcorner.com/UploadFile/rohatash/gridview-paging-sample-in-Asp-Net/
---
Hope this helps.
David Smith12y ago
Riddhi Valecha,

I am putting a software document together. We are migrating from Visual Basic 6.0 to C sharp. They are commands in Visual Basic 6.0 that's not supported in C sharp. I listed the above command in Visual Basics 6.0 in the first thread. I basically want to know a sample logic in c sharp using a datatable with the visual basic command properties below. The commands below are not supported in c sharp. So what is the c sharp equivalent logic to the command below using a disconnected datatable?

We are moving from recordsets to datatable
Close, Open, Update, UpdateBatch, AbsolutePosition, Find, Delete, MoveFirst, MoveNext, MoveLast, in visual basic 6.0 using a disconnected dataset (Datatable)?
Riddhi Valecha12y ago
I think you are developing a search engine...

Move next and Previous...
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Please explain your requirement again...