jwcolby
jwcolby at colbyconsulting.com
Tue Dec 11 14:07:02 CST 2007
OK, but do you understand ADO enough to do it without all of that stuff? Let me say that I am not an ADO kinda guy yet, and then let me show you what I am up against. Here is some actual "example code" for doing this stuff: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click ' Creating connection and command sting Dim conStr As String = "Provider=Microsoft.JET.OLEDB.4.0;data source=c:\\northwind.mdb" Dim sqlStr As String = "SELECT * FROM Employees" ' Create connection object Dim conn As OleDbConnection = New OleDbConnection(conStr) ' Create data adapter object Dim da As OleDbDataAdapter = New OleDbDataAdapter(sqlStr, conn) ' Create a dataset object and fill with data using data adapter's Fill method Dim ds As DataSet = New DataSet da.Fill(ds, "Employees") ' Attach dataset's DefaultView to the datagrid control DataGrid1.DataSource = ds.DefaultViewManager End Sub Now let me ask some questions so that you can perhaps understand how I am confused... >Dim da As OleDbDataAdapter = New OleDbDataAdapter(sqlStr, conn) Does this actually LOAD the data? Why pass in strSQL if not? >da.Fill(ds, "Employees") This obviously fills the data adapter, but is "Employees" the NAME of the table internal to the data adapter? Or is it the name of the table in the database? Is it just a reference to a dataset inside of the DA? Intellisense says that I am providing "srcTable" which would indicate that I am asking the data adapter to go look for "Employees" in SQL Server and fill DS with that. If that is the case then why did we do a "SELECT * FROM EMPLOYEES" in the SqlStr? This example is just a mess, and I haven't really found examples where they discuss what is actually happening in any depth. John W. Colby Colby Consulting www.ColbyConsulting.com -----Original Message----- From: dba-vb-bounces at databaseadvisors.com [mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of Charlotte Foust Sent: Tuesday, December 11, 2007 1:17 PM To: dba-vb at databaseadvisors.com Subject: Re: [dba-VB] Open a filtered form We are, but a lot of our code would make no sense outside the context of our framework. Our dataentities (classes that wrap and implement a typeddataset) return a dataset with defaults for the primary keys when appropriate. They also enforce the business rules that prevent saving a record without filling in required fields. We use a NewRecord routine in the form when we need to create a new datarow and populate those values and any other required values before adding the row to the dataset. You can hide columns in the grid without removing them from the dataset. And you can use SQL and ADO to create a recordset with only the specific fields provided for in the commandtext. Our OleDbProvider project includes the standard SQL for filling datasets as defined by the interface classes in the data project. It also includes data provider classes that implement the interfaces and actually return the filled datasets to the data entities. So, in short, code in the form sets the datasource of the grid to the dataset object, but the dataset object is filled in the OleDbProvider classes and handed back to the dataentity class bound to the form. We usually bind a grid to a dataview because it's easy to filter down to just the records you need and it gives you lots of control over the behavior. In many ways it's just like Access, especially if you have a rich data layer to program against instead of going straight against the objects exposed in Server Explorer. You can program against that with full intellisense without being attached to a database until you run the application. Charlotte Foust -----Original Message----- From: dba-vb-bounces at databaseadvisors.com [mailto:dba-vb-bounces at databaseadvisors.com] On Behalf Of jwcolby Sent: Tuesday, December 11, 2007 8:51 AM To: dba-vb at databaseadvisors.com Subject: [dba-VB] Open a filtered form Someone here must be opening forms filtered down to a set of records? I need to select a record in a main form and then open another form filtered to records related to the main form. The equivalent of the popup filtered forms from Access. Can anyone show code to cause this to happen? Let's assume for the moment a grid control in the popup form. I assume code in the form will create a data set object and bind the grid to that. I don't want the whole table though, I only want a set of records, a WHERE. And if I enter records I need the PKID from the parent table automagically entered in the new records I am creating. And I don't want the FK field from the parent object displayed in the grid. You know, "just like Access does it", and of course "just like you would logically expect it to be done". Is anyone doing this stuff? John W. Colby Colby Consulting www.ColbyConsulting.com _______________________________________________ dba-VB mailing list dba-VB at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-vb http://www.databaseadvisors.com _______________________________________________ dba-VB mailing list dba-VB at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/dba-vb http://www.databaseadvisors.com