C# Tutorial MSM_Murach chapter-18-slides

Murach’s C# 2010, C1 © 2010, Mike Murach & Associates, Inc. Slide 1
Chapter 18
How to work with data
sources and datasets

Objectives
Applied
1. Use a data source to get the data that an application requires.
2. Use a DataGridView control to present the data that’s retrieved
by a data source.
3. Use other controls like text boxes to present the data that’s
retrieved by a data source.
4. Write the code for handling any data errors that result from the
use of the data source or the controls that are bound to it.
5. Use the Dataset Designer to (1) view the schema for the dataset
of a data source, (2) modify a query using the Query Builder,
(3) preview the data for a query, or (4) review the SQL
statements that are generated for a data source.

Objectives (continued)
Knowledge
1. Describe the use of a connection string in an app.config file.
2. Describe the use of the Fill method of the TableAdapter object and
the UpdateAll method of the TableAdapterManager object.
3. Describe the use of the EndEdit method of the BindingSource
object.
4. Describe the two categories of data errors that can occur when you
run an application that uses a data source.
5. Describe the use of the DataError event for a DataGridView control.
6. In general terms, describe the way the SQL statements that are
generated for a data source (1) prevent concurrency errors and
(2) refresh a dataset when the database generates the keys for new
rows.

An empty Data Sources window

A Data Sources window after a data source has
been added

The first step of the Data Source Wizard

The second step of the Wizard

The third step of the Wizard

The Add Connection
dialog box

The Change Data Source dialog box

The fourth step of the Wizard

The information that’s stored in the app.config file
<connectionStrings>
<add
name="ProductMaintenance.Properties.Settings.
MMABooksConnectionString"
connectionString="Data Source=localhostsqlexpress;
Initial Catalog=MMABooks;
Integrated Security=True"
providerName="System.Data.SqlClient" />
</connectionStrings>

The last step of the Wizard

How to work with columns that have default
values
• Omit columns with default values from the dataset unless they’re
needed by the application.
• Provide values for those columns whenever a row is added to the
dataset.

A project with a dataset defined by a data source

A form with the Products table dragged onto it

The controls and objects that are created when
you drag a data source to a form
• DataGridView control
• BindingNavigator control
• BindingSource object
• DataSet object
• TableAdapter object
• TableAdapterManager object

The user interface for the Product Maintenance
application

The code that’s generated by Visual Studio
private void Form1_Load(object sender, EventArgs e)
{
// TODO: This line of code loads data into the
// 'mMABooksDataSet.Products' table.
// You can move, or remove it, as needed.
this.productsTableAdapter.Fill(
this.mMABooksDataSet.Products);
}
private void productsBindingNavigatorSaveItem_Click(
object sender, EventArgs e)
{
this.Validate();
this.productsBindingSource.EndEdit();
this.tableAdapterManager.UpdateAll(
this.mMABooksDataSet);
}

The syntax of the Fill method
tableAdapter.Fill(dataSet.TableName)
The syntax of the UpdateAll method
tableAdapterManager.UpdateAll(dataSet)

How to change the default control for a data table

How to change the default control for a column in
a data table

A form with the Customers table dragged onto it

The user interface for the Customer Maintenance
application

The code for the application
{
// TODO: This line of code loads data into the
// 'mMABooksDataSet.Customers' table.
// You can move, or remove it, as needed.
this.customersTableAdapter.Fill(
this.mMABooksDataSet.Customers);
}
private void customersBindingNavigatorSaveItem_Click(
object sender, EventArgs e)
{
this.Validate();
this.customersBindingSource.EndEdit();
this.tableAdapterManager.UpdateAll(
this.mMABooksDataSet);
}

.NET data provider exception classes
• SqlException
• OracleException
• OdbcException
• OleDbException

Common members of the .NET data provider
exception classes
• Number
• Message
• Source
• Errors
• GetType()

Code that catches a SQL exception
{
try
{
}
catch (SqlException ex)
{
MessageBox.Show("Database error # " + ex.Number +
": " + ex.Message, ex.GetType().ToString());
}
}

Common ADO.NET exception classes
• DBConcurrencyException
• DataException
• ConstraintException
• NoNullAllowedException
Common members of the ADO.NET classes
• Message
• GetType()

Code that handles ADO.NET errors
try
{
this.customersBindingSource.EndEdit();
this.tableAdapterManager.UpdateAll(this.mMABooksDataSet);
}
catch (DBConcurrencyException)
{
MessageBox.Show("A concurrency error occurred. " +
"Some rows were not updated.", "Concurrency Exception");
}
catch (DataException ex)
{
MessageBox.Show(ex.Message, ex.GetType().ToString());
customersBindingSource.CancelEdit();
}

Code that handles ADO.NET errors (cont.)
catch (SqlException ex)
{
MessageBox.Show("Database error # " + ex.Number +
": " + ex.Message, ex.GetType().ToString());
}

An event of the DataGridView control
• DataError
Three properties of the
DataGridViewDataErrorEventArgs class
• Exception
• RowIndex
• ColumnIndex

Code that handles a data error for a DataGridView
control
private void productsDataGridView_DataError(
object sender, DataGridViewDataErrorEventArgs e)
{
int row = e.RowIndex + 1;
string errorMessage = "A data error occurred.n" +
"Row: " + row + "n" +
"Error: " + e.Exception.Message;
MessageBox.Show(errorMessage, "Data Error");
}

The schema displayed in the Dataset Designer

The Query Builder

The Preview Data dialog box

SQL that retrieves customer rows
SELECT CustomerID, Name, Address, City, State, ZipCode
FROM Customers
SQL that inserts a customer row and refreshes
the dataset
INSERT INTO Customers
(Name, Address, City, State, ZipCode)
VALUES (@Name, @Address, @City, @State, @ZipCode);
FROM Customers
WHERE (CustomerID = SCOPE_IDENTITY())

SQL that updates a customer row and refreshes
the dataset
UPDATE Customers
SET Name = @Name,
Address = @Address,
City = @City,
State = @State,
ZipCode = @ZipCode
WHERE (
(CustomerID = @Original_CustomerID) AND
(Name = @Original_Name) AND
(Address = @Original_Address) AND
(City = @Original_City) AND
(State = @Original_State) AND
(ZipCode = @Original_ZipCode)
);
FROM Customers
WHERE (CustomerID = @CustomerID)

SQL that deletes a customer row
DELETE FROM Customers
WHERE (CustomerID = @Original_CustomerID) AND
(Name = @Original_Name) AND
(Address = @Original_Address) AND
(City = @Original_City) AND
(State = @Original_State) AND
(ZipCode = @Original_ZipCode)

C# Tutorial MSM_Murach chapter-18-slides

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C# Tutorial MSM_Murach chapter-18-slides