Data related instances:
data set
Friend Withevents DS1 As DGDataViewsample.DataSet1
DataSet1 is a data set frame file in the project, including two tables: TablePerson and TableType
Database connection variable
Friend WitHevents ODC as System.Data.Oledb.oledbConnection
This example uses the Access database, so the database connection uses the OLEDBConnection type. For different 3 database types, .NET provides different database connection classes.
For example, the SQL Server database requires SQLCONNECTION, ODBC data sources use ODBCCONNECTION, and Oracle databases need to use OracleConnection.
Data adapter
Friend WitHevents Oddaperson as system.data.oledb.oledbdataAdapter
Friend withevents oddatype as system.data.oledb.oledbdataadapter
Similar to database connections, different data adapter classes are required for different database types.
For example, the SQL Server database requires SqlDataAdapter, the ODBC data source uses ODBCDataAdapter, and the Oracle database needs to use OracleDataAdapter.
The properties of the data adapter can be added by the toolbar, follow the wizard hints; can be configured in the properties window during design; can be set in programming. A data adapter is equivalent to a data channel, which is responsible for popping data in the data source to the corresponding data set or data table, after completing the modification of the data set or data table, then submitting the updated data through the data adapter to Database source table. By modifying the corresponding SQL statement, you can use a programmable control data adapter to match different tables or views in the data source.
This example uses a separate data adapter and data view for each table for convenience.
Data view
Friend Withevents DVPERSON as System.Data.DataView
Friend Withevents DVTYPE As System.Data.DataView
This example uses a data view as a data source of DataGrid. Data sets and data sheets can also be used directly as a data source.
Data initialization:
When the initialization interface, two things need to be done, one is initialization data (in this example is the initdata process), populates the data in the data source into the data instance; the other is some of the control properties in the appropriate settings (this The initctrl process is used in the example to make the data correctly.
Initialization data
Private subinitdata ()
Try
Odc.open ()
Catch exception
MSGBOX (ex.Message)
Application.exit ()
END TRY
Try
Oddaperson.Fill (DS1.TablePerson)
Oddatype.Fill (DS1.TABLETYPE)
Catch exception
MSGBOX (ex.Message)
Application.exit ()
END TRY
End Sub
Initialization window control
Private subini ()
LbTable.selectedIndIndex = 0
Dg.select (0)
End Sub
Data browsing navigation:
First button
Private sub bfirst_click (byvale as system.object, byval e as system.eventargs) handles bfirst.clickdg.unselect (Dg.currentrowindex)
DIM DV AS DATAVIEW
DV = DG.DataSource
If DV.TABLE.ROWS.COUNT> 0 THEN
Dg.currentrowindex = 0
Dg.select (Dg.currentrowIndex)
END IF
End Sub
One button on the button
Private sub bprev_click (Byval E AS System.EventArgs) Handles BPREV.CLICK
Dg.unselect (Dg.currentrowindex)
DIM DV AS DATAVIEW
DV = DG.DataSource
IF DG.Currentrowindex - 1 <= 0 THEN
Dg.currentrowindex = 0
Else
Dg.currentrowindex = dg.currentrowindex - 1
END IF
Dg.select (Dg.currentrowIndex)
End Sub
Under the button
Private sub bnext_click (Byval e as system.EventArgs) Handles Bnext.click
Dg.unselect (Dg.currentrowindex)
DIM DV AS DATAVIEW
DV = DG.DataSource
IF dg.currentrowindex 1> = DV.TABLE.ROWS.COUNT THEN
Dg.currentrowindex = DV.TABLE.ROWS.COUNT - 1
Else
Dg.currentrowindex = DG.CurrenTrowIndex 1
END IF
Dg.select (Dg.currentrowIndex)
End Sub
The last one of the button
Private Sub Blast_Click (Byval E AS System.EventArgs) Handles Blast.click
Dg.unselect (Dg.currentrowindex)
DIM DV AS DATAVIEW
DV = DG.DataSource
Dg.currentrowindex = DV.TABLE.ROWS.COUNT - 1
Dg.select (Dg.currentrowIndex)
End Sub
Data operation
Button Add
Private Sub Badd_Click (Byval E AS System.EventArgs) Handles Badd.click
DIM DV AS DATAVIEW
DIM ROWNEW AS DATAROWVIEW
DV = DG.DataSource
ROWNEW = DV.AddNew ()
Rownew.endedit ()
Dg.currentrowindex = DV.TABLE.ROWS.COUNT - 1
Dg.select (Dg.currentrowIndex)
End Sub
After calling the AddNew Add a new record, the endedit is called, which indicates that this addition operation has been completed, and this new record can be done anything else. Before calling, the new record is considered to be edited, which will be locked, and the deletion of the operation will cause an error, and this record does not real deposit table. After the endedit call, the new record is stored in the table, but the line status is marked as a new record. After this step is completed, the user generally enters the new recorded field value through the table. In the program, it is actually a modification of the new record.
Button delete
Private sub bdel_click (Byval e as system.EventArgs) Handles BDEL.CLICK
DIM DV AS DATAVIEW
DV = DG.DataSource
Dv.delete (Dg.currentrowIndex)
Dg.select (Dg.currentrowIndex)
End Sub
Save button
Private sub bsave_click (Byval E AS System.EventArgs) Handles Bsave.click
Me.Updatedata ()
End Sub
Save child process
Private sub updatedata ()
Dim Addds as DataSet
DIM DELDS AS Dataset
DIM Updateds as DataSet
Try
Addds = DS1.Getchanges (DataRowState.Added)
Delds = ds1.getchanges (DATAROWSTATE.DELETED)
Updateds = DS1.Getchanges (DataRowState.Modified)
IF adds is nothing then
Else
ODDAPERSON.UPDATE (AddDS)
Oddatype.Update (AddDS)
END IF
IF updateds is nothing then
Else
Oddaperson.Update (Updateds)
Oddatype.Update (Updated)
END IF
IF Delds is nothing then
Else
Oddaperson.Update (DELDS)
Oddatype.Update (DELDS)
END IF
Catch exception
MSGBOX (ex.Message)
EXIT SUB
END TRY
Try
DvPerson.table.acceptchanges ()
DVTYPE.TABLE.ACCEPTCHANGES ()
DS1.acceptchanges ()
Catch exception
MSGBOX (ex.Message)
EXIT SUB
END TRY
End Sub
* After calling acceptchange for DataTable, the status flag of all rows will be cleared, that is, the program will not be able to distinguish what is newly added, which is modified. So all the operations that use the row status flag to modify the data source before this call.
* Sequence of various modifications to the data source is: Added rows - modified rows - the deleted row. To avoid logic errors during operation.
