Re: Program Design - Master DataSet/Adapter for program? - Database Discussion Boards

Dear All,

can any one help me to give some sample code on how to access *.dbf file using c#

Thanks in advance

Look in the documentation for the System.Data.SqlClient namespace.

DBF are DBase files, they may be 1 of several versions including foxpro. Using a DBase IV driver would be the first step as this used support most versions but you may need to install and test a few to get the correct driver.

You should be able to open it with Access and it may give you some clues as to the version.

Once you have the driver installed you simply use a connection string as any other database.

Never underestimate the power of human stupidity
RAH

Good heavens OMG | :OMG:

Is dbf still alive and kicking? The last time I used it was over two decades ago and I thought it was already buried... deep.

The need to optimize rises from a bad design.My articles[^]

Every now and then it raises it's head, we currently have to use a foxpro driver to access a bastardised version of a DBase IV format. Someone released a NEW dbf viewer this year so it is still around.

Never underestimate the power of human stupidity
RAH

Thanks fo ryour reply,

FYI, I have using the ODBC connection to connect the *.dbf file before and it's working fine ,and i don't know why know , suddently i have problem to connecting to the database.
I have attached my source code for your refference.Plzzzzzzzz guide me on how to solve tyhis problem

using System.Data.Odbc;

string thisConnection = @"Driver={Microsoft dBASE Driver (*.dbf)};SourceType=DBF;SourceDB=C:\data\;Exclusive=No; Collate=Machine;NULL=NO;DELETED=NO;BACKGROUNDFETCH=NO;";
string sql = @"SELECT * FROM C:\data\QC.dbf";
OdbcConnection conn = new OdbcConnection(thisConnection);
OdbcCommand cmd = new OdbcCommand(sql);
cmd.Connection = conn;
OdbcDataReader reader = null;
try
{
conn.Open();
reader = cmd.ExecuteReader();
while (reader.Read())
{
MessageBox.Show(reader[1].ToString());
}
reader.Close();
}
catch (OdbcException err)
{
MessageBox.Show(err.Message);
}
finally
{
conn.Close();
}

Hi All! I am new to using the .NET framework database objects and have a question about how to design my program using Adapter/DataTable queries.

My Database...My database consists of about 10 different tables. No one table is indepedent. All have at least one relationship with another table.

My Program...The program needs to be designed such, that when the user clicks "OK" on whichever dialog, the program will commit the new data to the database.

Here is the jist of what I'm curious about...What is best design for the interaction between my OleDbDataAdapter and the DataSet or DataTables? Do you think these objects should be created with each form? When I need to run a query involving two tables using OleDbCommand it seems I have to use an adapter which then reads the database on disk and not an In-memory object.

Currently, on startup my program reads each table into a DataSet object. For basic queries involving a single table this works fine (using the Select method of DataTable). But anything more complex I now need to create a new DataAdapter and DbCommand objects.

Would it be reasonable to have one OleDbConnection object for application. Then mutiple OleDbAdapter objects for each form. I would also have a OleDbCommandBuilder in each form to allow for the Update method when user wants to commit data.

To illustrate my startup code is below.

Thanks for your help!!!

            m_dsPTData = New DataSet<br />
<br />
            m_dbConnection = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & strFilename)<br />
            m_dbConnection.Open()<br />
<br />
            m_dbDataAdapter = New OleDbDataAdapter()<br />
<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM Congregations", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "Congregations")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM HomeTalks", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "HomeTalks")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM CongregationSpeakers", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "CongregationSpeakers")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM CongregationSpeakerOutlines", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "CongregationSpeakerOutlines")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM Outlines", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "Outlines")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM OutlineCategories", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "OutlineCategories")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM Readers", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "Readers")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM Chairmen", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "Chairmen")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM Hospitality", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "Hospitality")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM AwayTalks", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "AwayTalks")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM Notes", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "Notes")<br />
            m_dbDataAdapter.SelectCommand = New OleDbCommand("SELECT * FROM Conductors", m_dbConnection)<br />
            m_dbDataAdapter.Fill(m_dsPTData, "Conductors")<br />
<br />
            Dim commandBuilder As OleDbCommandBuilder = _<br />
                New OleDbCommandBuilder(m_dbDataAdapter)<br />
<br />
            m_dbConnection.Close()<br />

I think your post would have been better off in Design and Architecture forum, but anyway.

David Hovey wrote:
when the user clicks "OK" on whichever dialog, the program will commit the new data to the database

Just a note: Take care that database operations are done transactionally and no user interference is allowed while transaction is running.

David Hovey wrote:
Do you think these objects should be created with each form

Forms and data (and logic) should be separated so that you can modify each (almost) independently. Get to know for example MVC (Model-View-Controller) concept.

David Hovey wrote:
When I need to run a query involving two tables using OleDbCommand it seems I have to use an adapter which then reads the database on disk

I don't see any reason why you should store the results to a disk. You use joins in the SQL statement.

David Hovey wrote:
But anything more complex I now need to create a new DataAdapter and DbCommand objects

That would be logical in many cases, although you can reuse the command if you change the command text.

David Hovey wrote:
Would it be reasonable to have one OleDbConnection object for application

You should get and open the connection to the database when you need to operate with it. After executing the statements, you close the connection. Also use connection pooling.

David Hovey wrote:
Then mutiple OleDbAdapter objects for each form

Again, separate forms and database operations. For example if you someday want to run the logic on a middle-tier and only the UI on client (or web page) it greately helps you if you have a good and logical layering in your code.

David Hovey wrote:
I would also have a OleDbCommandBuilder in each form to allow for the Update method when user wants to commit data.

Same as previous, but note what I wrote in the beginning about transactions and user interference.

Hope this helps you forward,

Mika

The need to optimize rises from a bad design.My articles[^]

It does very much. I found a PDF of excerpt from a book "Object-Orientated Development with ActionScript 2.0" (chapter 18) that talks about MVC.

I can see the basic concepts of each part of MVC and I can see the benefits, but exactly how to relate it to my program is difficult.

The example in the book is a Clock with digital and analog views. Rather simple.

Can you help me a beginning question I have though? From my understanding each View should have one Controller. Does that mean the Controller is designed specifically for that particular view?

WTF | :WTF:

This sure does require alot more planning that the way I was going about it. It will take more time...

Will need to study MVC further obviously.

David Hovey wrote:
how to relate it to my program is difficult

In the beginning it is, but don't worry. When you get over the 'new concepts' and 'ideology that changes everything' part you actually discover that it's no rocket sience. Just a new three (or four) letter abbreviation to a very simple and logical thing.

I think there are several good articles about MVC at this site, have a look at them, for example: Building an MVP Framework for .NET. Part 1: The Basics of MVC and MVP[^]

David Hovey wrote:
each View should have one Controller

That's the basic idea but in some implementations one controller can have several views.

David Hovey wrote:
This sure does require alot more planning that the way I was going about it

It does, but you don't have to use Visual Studio or Rational Rose etc. In the simplest form it's basic OOP principles and what code do you write and where. So actually what I typically use is pencil and paper. Well, lots of paper because the first versions always go to the garbage pin Smile | :)

David Hovey wrote:
It will take more time

It will in this project, but you also learn a lot. That's an investment!

The need to optimize rises from a bad design.My articles[^]

I am trying to connect SQL Server 2005 with asp.net there is one problem
Kindly reply me quick as i able to do my work.

This is the problem

Could not load file or assembly 'Microsoft.SqlServer.Management.Sdk.Sfc,Version = 10.0.0.0,Culture = neutral, PublicKey Token = 89845dcd8080cc91'or one of its dependencies.

At a guess Id say that its failing to load an assembly. Have you added all required references?

One reason may be if you previously had SQL Server 2008 installed on this machine and then unistalled it. If this is the case, try reinstalling SQL Server 2008 client files.

The need to optimize rises from a bad design.My articles[^]

Hi,

I have an Access database which was converted to Access 2007. The file is about 60MB big. When I double click it, the application opens up, and all that I see is an input form, looks almost like a Windows application. I need to see the database structure "behind" it with all the tables. How do I see it? Currently I can just see the input form.

Please can someone advise.

Thanks
Brendan

Is this a compiled database? If yes, then you cannot view the tables or other objects at all...

If not - Do you get a warning message appearing when you try to open the database, asking if it is safe to open? Depress the Shift key and click on the Open button - this should take you to the design mode. This works in Access 2003 - not sure about 2007, though.

HTH

Someone forgot to assign you an Administrator role.

The world is a stage and most of us are desperately unrehearsed.
—Sean O’Casey, Playwright

hi i am trying to create a new database role with the name "EmpSelf" but i am getting the error as role already exist but i am unable to find that role ? please help me any one who know this !...

Awaiting Reply ....

TITLE: Microsoft SQL Server Management Studio
------------------------------

Create failed for DatabaseRole 'EmpSelf'. (Microsoft.SqlServer.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=9.00.1399.00&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Create+DatabaseRole&LinkId=20476

------------------------------
ADDITIONAL INFORMATION:

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

------------------------------

User, group, or role 'EmpSelf' already exists in the current database. (Microsoft SQL Server, Error: 15023)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=09.00.1399&EvtSrc=MSSQLServer&EvtID=15023&LinkId=20476

------------------------------
BUTTONS:

OK
------------------------------

You can use for example sp_helprole[^] to list all roles in a database.

The need to optimize rises from a bad design.My articles[^]

Iam using a table variable inside a stored procedure to search for a name. When executing the stored procedure for the first time in my asp.net web application it times out, while the second time it takes 3 seconds and less.

How can i getrid of this time out the first time?

Here is my SP:

ALTER PROCEDURE [dbo].[SearhBYFullName]
@FullName nvarchar(250)=null,
@Language varchar(10)=null,
@TableName varchar(50)=null,
@BadInfo bit=null,
@Client bit=null,
@Source nvarchar(50)=null,
@top int=1000,
@Filter varchar(10)=null
AS
BEGIN
Declare @Tmp_SearchByName table(
pk int identity(1,1),
RefId int ,
FullName nvarchar(200),
TableName varchar(50),
TableOrder varchar(50))

insert into @Tmp_SearchByName(RefId,FullName, TableName, TableOrder)
(
SELECT DISTINCT RefId,FullName, TableName, TableOrder from table1 where FullName=@FullName
union
SELECT DISTINCT RefId,FullName, TableName, TableOrder from table2 where FullName=@FullName
union
SELECT DISTINCT RefId,FullName, TableName, TableOrder from table3 where FullName=@FullName
union
SELECT DISTINCT RefId,FullName, TableName, TableOrderc from table4 where FullName=@FullName
union
SELECT DISTINCT RefId,FullName, TableName, TableOrder from table5 where FullName=@FullName
)

SELECT distinct top(@top) tmp.RefId, tmp.TableName, tmp.TableOrder, tmp.FullName,
Reference.RefSourceId, Reference.RefNumber, StRefSource.Code as source,
StRefSource.Description
FROM @Tmp_SearchByName tmp
INNER JOIN Reference ON tmp.RefId = Reference.RefID
INNER JOIN StRefSource ON Reference.RefSourceId = StRefSource.Id
left outer join vw_SelectClients as BA on BA.Refid=tmp.RefId
where ((tmp.TableName=@TableName and @TableName is not null) or @TableName is null)
and ((BA.Code='BA' and @Client is not null) OR @Client is null)
order by tmp.TableOrder,StRefSource.Code,tmp.FullName,tmp.RefId

Without any information about the data amounts etc I would guess that the operation just takes too long.

Why this happens only for the first time sounds like that second time you execute this, buffer manager has enough data to execute the whole thing in acceptable time. This isn't the case when executing the procedure first time (most likely because of high physical I/O amount).

Based on the statements I would say that you need to optimize your statements. Investigate the execution plan for all of the statements and try to eliminate the bottlenecks. To achieve good performance results you may even have to rethink the e/r-model.

The need to optimize rises from a bad design.My articles[^]

Hi,
I need to exceute a query in my DB when the postgres service starts .
Is there any means to achieve this.
I tried calling an exe when system starts it worked but need to exceute as soon as the service starts .

Thanks

I don't know if Postgres supports executing statements at startup, but one way to do this is to create a simple wrapper which:
- starts up the database
- gets a connection
- executes the statement.

In this case you would set the postgres service startup option to manual and start it using the wrapper. If you want, you can create the wrapper as a service which then again is set to start automatically.

The need to optimize rises from a bad design.My articles[^]

hello forum

i want to give an option of search on frontend (asp.net) that will find the given keyword in selected columns of each table present in database
how can i do that perfectly and without effecting the performance.

How to create a stored procedure to apply a search on every table in a database

can anybody help me.

regards
rahul

Assuming SQL Server 2005/2008 there is a built in command called sp_MSForEachTable

exec sp_MSForEachTable @command1 = "select col1 from ? where x = y"

Note the use of double quotes around the command. When the query runs it replaces the question mark with the table name. I have a feeling you made need single quotes around the question mark, but I don't have sql server on this pc to check.

Hopefully this will get you in the right direction

Bob
Ashfield Consultants Ltd

Thanx Friend

I m working on that....

regards
Rahul