This small application for
DataGrid allows users to:
- add a new row in the
- save or update a row of the
- delete an existing row from the
- read the data from an XML file.
- copy the current data of the
DataSet to three files on C:\ root directory:
- MyXMLText.txt (text file)
- MyXMLdata.xml (XML file)
- MyXMLschema.xsd (schema file)
- write the current data of the table to a text file on C:\.
DataGrid control in the "DataGrid Application" binds to a single
DataSet object. The
DataSet object of the "DataGrid Application" is initially populated from a database using an
What is a DataGrid?
The Windows Forms
DataGrid control provides a user interface to ADO.NET datasets, displays ADO.NET tabular data in a scrollable grid, and allows for updates to the data source. In cases where the
DataGrid is bound to a data source with a single table containing no relationships, the data appears in simple rows and columns, as in a spreadsheet. The
DataGrid control is one of the most useful and flexible controls in Windows Forms. As soon as the
DataGrid control is set to a valid data source, the control is automatically populated, by creating columns and rows based on the structure of the data. The
DataGrid control can be used to display either a single table or the hierarchical relationships between a set of tables.
For example: if you bind the
DataGrid to data with multiple related tables, and if you enable navigation on the
DataGrid displays so called 'expanders' in each row.
With an expander, you can navigate from a parent table to a child table. If you click a node in the
DataGrid, it displays the child table. If you click the Back button, it displays the original parent table. In this fashion, the grid displays the hierarchical relationships between tables.
Bear in mind that only one table can be shown in the
DataGrid at a time. Valid data sources for the
- A single dimension array
- Any component that implements the
How to display data in the DataGrid programmatically?
If you want to display data in a
DataGrid, you need to define a
DataGrid object. There are, of course, different ways to populate the data in the
DataGrid. For example:
Define first a
DataGrid and declare a new
DataGrid, and then set some properties of the
DataGrid (location, name, size etc..).
private System.Windows.Forms.DataGrid dataGrid1;
this.dataGrid1 = new System.Windows.Forms.DataGrid();
this.dataGrid1.Location = new System.Drawing.Point(16, 40);
this.dataGrid1.Name = "dataGrid1";
this.dataGrid1.Size = new System.Drawing.Size(256, 176);
Now we can put all the commands needed into a method "
fnDisplayDataInDataGrid()", to display data in the
private void fnDisplayDataInDataGrid()
string conStr ="Integrated Security=SSPI;" +
"Initial Catalog=Northwind;" +
SqlConnection conn = new SqlConnection(conStr);
SqlDataAdapter adapter = new SqlDataAdapter("SELECT * FROM MyTable", conn);
DataSet ds = new DataSet();
At this point, I would refer you to my previous article (Using ADO.NET for beginners) where you can find some more interesting tips and tricks for
DataGrids (i.e., how to trap keystroke events - Up, Down, Escape etc. - in a
How It Works
After you get connected to the MS Access database, all records are displayed on the
When you run the application first time, the method "
fnRefresh()" will be called. It clears the contents of the
DataSet, fills the
DataAdapter, and displays the data from the data source in the
DataGrid. After that, all the buttons are ready to be used. Here is the code snippet of the method "
private void fnRefresh()
Insert a new row
If you click the "Insert" button to add a new record, the last row on the
DataGrid is selected and the previous clicked row is unselected. After entering the data for that row, you click the 'Save/Update'-button to save the new row. Here is the method for inserting a new row:
private void fnInsertNew()
MessageBox.Show("Enter the new record at the end" +
" of the DataGrid and click 'Save/Update'-button", "Stop");
Save or Update the new/changed row(s)
The code snippet for the method "
fnSaveUpdate()" saves the changes that are made to the
DataSet back to the database. The '
GetChanges' method of
dataSet11 will return a new
DataSet which is called '
myChangedDataset' containing all the rows that have been modified (updated, deleted or inserted). If no changes have been made, the method '
GetChanges' returns a '
If any sort of error occurs while updating the database, the '
Update' method of
OleDbDataAdapter will generate an exception. This logic is held in a
catch block. If an exception occurs, you get a message box informing you of the error. And the "
RejectChanges" method is then called to discard the changes you made. If any changes are made, the user is told how many rows were affected/changed, and the "
AcceptChanges()" method will mark the changes made as permanent in the
DataSet. Now we need to invoke refreshing the
DataSet with the method "
fnRefresh()". I think this is a 'simple' and robust technique when updating the database.
Here is the code snippet for the '
private void fnSaveUpdate()
DataSet myChangedDataset= this.dataSet11.GetChanges();
if (myChangedDataset != null)
int modifiedRows = this.oleDbDataAdapter1.Update(myChangedDataset);
MessageBox.Show("Database has been updated successfully: " +
modifiedRows + " Modified row(s) ", "Success");
MessageBox.Show("Nothing to save", "No changes");
MessageBox.Show("An error occurred updating the database: " +
ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
Delete the current row
It is always a good practice to ask the user before deleting a row. After clicking 'Yes', the current row on the
DataGrid is deleted, updated and refreshed. The method for deleting a row is as below:
private void fnDelete()
DialogResult dr=MessageBox.Show("Are you sure you want to delete this row ? ",
"Confirm deleting", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
if (dr ==DialogResult.Yes)
DataTable tbl=new DataTable("MyContactsTable");
Reading the data from an XML file
Sometimes you have to read the data from an XML file and display it in a
DataGrid. In order to do this, I pass the XML file to the method; if the file exists, I clear the
DataSet and read the XML data into the
DataSet using the specified file. The following code snippet shows this:
private void fnDataReadingFromXMLFile(string filename)
if ( File.Exists(filename))
MessageBox.Show("Data reading from "+filename+" -file");
MessageBox.Show(filename + " does NOT exist; Please click" +
" first the button 'CopyToXML' ", "File Error",
MessageBoxButtons.OK, MessageBoxIcon.Error );
Copy the DataSet to the Text / XML / Schema file
Clicking the 'CopyToXML' button invokes the '
fnCopyToXMLandTextFile()' method. As you can guess from its name, it writes the current data of the
DataSet to three files on the C:\ root directory:
- Text file: MyXMLdataText.txt.
- XML file: XMLdata.xml.
- Schema file: MyXMLschema.xsd.
If you wish to use another path instead of 'C:\', you have to change the code accordingly. The following code snippet demonstrates this feature:
private void fnCopyToXMLandTextFile()
if (this.dataSet11 == null)
string s="The current data of the DataSet coppied on C:\\ as: \n";
s +="* Text file: MyXMLdataText.txt\n";
s +="* XML file: XMLdata.xml\n";
s +="* Schema file: MyXMLschema.xsd";
MessageBox.Show(s, "Copy to XML/Text/Schema file");
Writing the current data of the table into a text file on hard disk (C:\)
ExecuteReader requires an open and available connection, first we have to open the database connection. If the connection's current state is
Closed, you get an error message. After opening the connection, we create an instance of
CommandText for the SQL statement, an
OleDbDataReader and an instance of
StreamWriter. And then, in a
OleDbDataReader reads through the data rows and writes them out to the text file. Finally, it closes the
StreamWriter writer = new StreamWriter("C:\\MyTextFile.txt", false), we pass the the text file and set the
bool value to '
false'. If the file doesn't exist, in any case a new text file will be created. If the file exists and it the second parameter is '
false', the file will be overwritten because of '
false'. If the value is '
true', then the file won't be overwritten and the data will then be appended to the file. Here is the code snippet for writing to the text file:
private void fnWriteToTextFile()
OleDbCommand cmd=new OleDbCommand();
cmd.CommandText="SELECT Address, City, Country, Email," +
" FirstName, LastName, Message, Phone FROM MyContactsTable";
using (StreamWriter writer = new StreamWriter("C:\\MyTextFile.txt",false))
}catch (Exception excp)
MessageBox.Show("Data of table writtten into" +
" C:\\MyTextFile.txt file","Writing completed");
I think the code is quite simple to understand because I tried to make comments to almost every line of code. I hope you can find something useful here for your projects. As ever, all feedback is welcome. For more tips about the
DataGrid, here is the link of my other article: Using ADO.NET for beginners.
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