For a while now, I'm a member of CodeProject family, and I've never contributed any of my projects. Since this site has been very helpful for me while learning C#, I've decided to share my first project in C#. It was written about a year ago when I joined here. Anyhow, this article is about a simple database built in Microsoft Access and C#. I wanted to explore this because the end user doesn't need to install any SQL servers, he just needs executable binary and *.mdb file. As I mentioned, it is one of my first projects, so it is not very advanced, but the provided code snippets are useful, i.e. connecting to *.mdb file, read/write data, using dataGridView control, adding buttons to cells, etc.
First, you need to create a database in Microsoft Access. The database is very simple and therefore, there is a lot of scope for future work and improvement.
// First table contains movies
// where movieID is auto-increment value, also primary key, and typeID foreign key
// movies (movieID, Title, Publisher, Previewed, Year, typeID)
// ---------------------------------------------------------------
// Second table contains movie types
// movietypes (typeID, Type)
If you have a bigger database in your mind, you can use some generator to create the database. For a small project like this, those kinds of tools aren't necessary (also, try to keep it in 3NF).
Ok, now we have our database. Microsoft Access allows us to add records, but we want to create our own front end. To be able to connect to the database and manipulate with records, it is necessary to use the System.Data.OleDb namespace which will provide the required methods.
In the constructor of the initial form, the application connects to the database using the following code:
public Form1()
{
InitializeComponent();
// initiate DB connection
string connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;
Data Source=moviedb.mdb";
try
{
database = new OleDbConnection(connectionString);
database.Open();
//SQL query to list movies
string queryString = "SELECT movieID, Title,
Publisher, Previewed, Year, Type
FROM movie,movieType WHERE movietype.typeID = movie.typeID";
loadDataGrid(queryString);
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
return;
}
}
The method loadDataGrid loads the data from the database to the dataGridView control, using the SQL query in the string variable, queryString. Here is the implementation:
public void loadDataGrid(string sqlQueryString) {
OleDbCommand SQLQuery = new OleDbCommand();
DataTable data = null;
dataGridView1.DataSource = null;
SQLQuery.Connection = null;
OleDbDataAdapter dataAdapter = null;
dataGridView1.Columns.Clear(); // <-- clear columns
SQLQuery.CommandText = sqlQueryString;
SQLQuery.Connection = database;
data = new DataTable();
dataAdapter = new OleDbDataAdapter(SQLQuery);
dataAdapter.Fill(data);
dataGridView1.DataSource = data;
dataGridView1.AllowUserToAddRows = false; // <-- remove the null line
dataGridView1.ReadOnly = true; // <-- so the user cannot type
// following code defines column sizes
dataGridView1.Columns[0].Visible = false;
dataGridView1.Columns[1].Width = 340;
dataGridView1.Columns[3].Width = 55;
dataGridView1.Columns[4].Width = 50;
dataGridView1.Columns[5].Width = 80;
// insert edit button into datagridview
editButton = new DataGridViewButtonColumn();
editButton.HeaderText = "Edit";
editButton.Text = "Edit";
editButton.UseColumnTextForButtonValue = true;
editButton.Width = 80;
dataGridView1.Columns.Add(editButton);
// insert delete button to datagridview
deleteButton = new DataGridViewButtonColumn();
deleteButton.HeaderText = "Delete";
deleteButton.Text = "Delete";
deleteButton.UseColumnTextForButtonValue = true;
deleteButton.Width = 80;
dataGridView1.Columns.Add(deleteButton);
}
The interesting part of this code is adding buttons to dataGridView cells. Using these buttons, you can update or delete the selected row. The other way to do this is to place only two buttons outside the dataGridView control, and then select the row you want to edit/delete and press the button. Here, every row has its own buttons.
The question remains, how can I detect when the button is pressed, and where do I place my code to do some action. Well, here is the way to do it:
private void dataGridView1_CellContentClick
(object sender, DataGridViewCellEventArgs e)
{
string queryString = "SELECT movieID, Title, Publisher,
Previewed, Year, Type
FROM movie, movieType WHERE movietype.typeID = movie.typeID";
int currentRow = int.Parse(e.RowIndex.ToString());
try
{
string movieIDString = dataGridView1[0, currentRow].Value.ToString();
movieIDInt = int.Parse(movieIDString);
}
catch (Exception ex) { }
// edit button
if (dataGridView1.Columns[e.ColumnIndex] == editButton && currentRow >= 0)
{
string title = dataGridView1[1, currentRow].Value.ToString();
string publisher = dataGridView1[2, currentRow].Value.ToString();
string previewed = dataGridView1[3, currentRow].Value.ToString();
string year = dataGridView1[4, currentRow].Value.ToString();
string type = dataGridView1[5, currentRow].Value.ToString();
Form2 f2 = new Form2();
f2.title = title;
f2.publisher = publisher;
f2.previewed = previewed;
f2.year = year;
f2.type = type;
f2.movieID = movieIDInt;
f2.Show();
dataGridView1.Update();
}
...
I used the CellContentClick event. So now, when the button is down, I need to know the selected row. I do this by using the e.RowIndex. Using this variable, you can fetch any column value of the selected row. As shown, the first parameter is column index, and the second is row index. When the update of the selected row is completed in Form2, now using the Update() method on the dataGridView1 object, you can see the changes that were made.
The delete button works the same way.
// delete button
else if (dataGridView1.Columns[e.ColumnIndex] ==
deleteButton && currentRow >= 0)
{
// delete SQL query
string queryDeleteString =
"DELETE FROM movie WHERE movieID = "+movieIDInt+"";
OleDbCommand sqlDelete = new OleDbCommand();
sqlDelete.CommandText = queryDeleteString;
sqlDelete.Connection = database;
sqlDelete.ExecuteNonQuery();
loadDataGrid(queryString);
}
This project shows a simple way how to use Microsoft Access database and .NET controls to display stored data. Everything that you need to start your own more advanced application for a similar purpose is shown here. The project is for C# beginners, and with a little bit of imagination, it can be improved and useful. Hope you like it. Cheers!!
SelectionMode property to dataGridView1| You must Sign In to use this message board. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
how i can simply join C# with tables in access and how i can only read from it and take some values? 
