1. ADO.NET in VB.NET 2005
ITE 370
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2. What is ADO.NET?
An acronym for the .NET version of ActiveX Data Objects
A .NET Framework Class Library
A group of types that reside in System.Data namespace
A technology used by client applications to work with stored data
Supported data formats include:
relational databases (MS-Access, SQL-Server, and Oracle)
Spreadsheets and other file formats
XML
ADO.Net are the Active X Data Objects in Visual Studio –
They connect application program to data sources (Relational Databases, Excel Spreadsheets, etc.)
Resides in System.Data namespace (library) – We will need to Import System.Data.* in applications
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3. Providers and Their Namespaces
What is a “provider”?
.NET data provider
Software for accessing a specific source of data, such as SQL-Server
Optimized classes for SQL-Server
Namespace: System.Data.SqlClient
OLE DB client
For MS-Access, Excel, and others
Also has support for Oracle and SQL-Server
Namespace: System.Data.Oledb
Normally, since it has support of Access and Sql-Server we will import System.Data.Oledb
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4. How clients, .NET data providers &DBMSs fit together
SQL
.NET Data
Provider
OLE DB
other
.NET data
providers MS
Access
Server
Client – Our windows application. This can reside at a different physical location
We need to use the correct data provider to connect to the database
other
DBMS
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5. Types of ADO.NET objects
Connection – establishes links to data sources
Command – stores and executes commands (i.e. queries and stored procedures with parameters)
DataReader – provides sequential, read-only access to data
TableAdapter – pulls data from one or more database tables and passes it to your program
DataSet – an in-memory copy of data pulled from the database tables (by the Table Adapter)
DataTable – stores a relation—eg. the result of a query
DataRelation – defines a relationship between two DataTables
DataRow – stores a single row/record of a data table
DataColumn – represents schema in a column of a DataTable
DataView -- customized view of a DataTable for sorting, filtering, searching, editing, and navigation.
DataGrid – tabular control for displaying/editing a data source
We need to know what we want to do when we connect to the data source so we know what data objects we will need to create.
Search  Read
Edit  Modify
CRUD  Create / Read / Update / Delete
First focus on Connection, Command and Data Reader
Connection – Connect the application to the data
Supply the name and location of the Database Provider – the data source
Provide username and password
Verify connection
(This can be a maintained connection or a Just In Time Connection that is opened and closed as needed)
The Data Source is stored as a property of the Connection object
Command – Allows us the CRUD capabilities with the data source
Store Queries (Select, Insert, Update, Delete)
Use Stored Procedures with Parameters (Reside at the Database Tier)
Data Reader – Holds the data in the application program to allow use to work with the data
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6. Working with .udl files to build connection strings
To create a UDL file:
1.      Open Windows Explorer or My Computer.
2.      Select the folder in which you want to save the .UDL file.
3.      On the File menu, click NEW and then click Text Document.
4.      Right-click on the text file you created in step 3, then click Rename. Type the new file name using a .udl file extension. Press Enter. For example. Myudl.UDL
5.      You may get a warning, message box, explaining that changing file extensions may cause files to become unusable. This is fine, click OK.
Once you have created the UDL file, you must now configure it:
Double click on the UDL file to bring up the Data Link Properties Dialog Box.
Click on the Providers tab and select the driver you wish to use.
Click on the Connection tab and enter the connection properties, each driver will require different settings, so I will not go into much details. All drivers will require a user name and password.
Click on the “Test Connection” button to verify your connection is working correctly. Change accordingly if you get an error.
Select the advanced tab only if you require advanced settings.
The Data Like Wizard will build a data source property string that we will then paste into our programs
(Very complicated string, you can create yourself if you want to)
Access 2003 requires the Microsoft Jet 4.0 OleDB provider
An error on the connection could be a wrong version of the provider.
We can then open this file in Notepad to see (and later copy) the connection string.
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Source: K & K Consulting,

7. Create Data Source String for Connection Object
Example of how to create the Data Source String
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8. DataReader Class The DataReader
Provides forward-only, read-only access to data
Analogous to reading a sequential file
Read from beginning of file in order to the end of file
Fast access to data
Uses little memory
Requires connection and command objects to use
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9. DataReader Example Imports System.Data.Oledb Public Class ConnDb
'* Declare constant to hold base connection string information
'* for connecting to an MS-Access baseball database (connection string from UDL file).
Public Const ConnStr As String = "Provider=Microsoft.Jet.OLEDB.4.0;" _
& "Persist Security Info=False;Data Source=“ ‘* notice we removed name of file
End Class
'* Declare data access objects
Dim conTeamDb As OleDbConnection '* connects to baseball database
Dim dbCommand As OleDbCommand '* executes database query for team
Public rdrTeams As OleDbDataReader '* forward-only, read-only access to team relation
Dim OpenDbDialog As New OpenFileDialog
‘* If the user selects a database in the open dialog box...
If OpenDbDialog.ShowDialog() = DialogResult.OK Then
'* connect to the database
conTeamDb = New OleDbConnection(ConnDb.ConnStr & OpenDbDialog.FileName)
conTeamDb.Open()
'* query the team table, assigning result to a data reader
dbCommand = New OleDbCommand("SELECT Location, Nickname, Stadium, League FROM Team", conTeamDb)
rdrTeams = dbCommand.ExecuteReader
If rdrTeams.Read() '* success reading next team
Console.WriteLine(rdrTeams.Item("Location") & " " & rdrTeams("Nickname"))
End if
rdrTeams.Close()
conTeamDb.Close()
End If
Code Example of Data Reader
Storing the connection string as a constant (in fact it is stored as a class) allows us to use it throughout the application as necessary
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10. View Sample Project Using Data Reader
Create New VB.Net Application
Add ListTeams.VB
Project Properties  StartUP
Sub Main ( )
Run Sample Application Using Data Reader
Attempt to Add a Form and Have the Data Display within the Form instead of to the Console
Incorrect Queries will result in a Run Time Error (Create and test in the Database, then copy into the application)
Look in MSDN or Textbooks to find out more about the Connection, Command, and DataReader Objects.
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11. Using Table Adapters / Data Set
Table Adapter – Retrieves data from the data source and updates the data in the data source
Data Connection – Connecting to the Data Source
Built into the Table Adapter Object
Data Set – In memory copy of records / data tables
Separate from the data source
Data tables have columns and rows
Allows you to work with the data from the data source
Changes are not permanent in external data source unless directed by the Table Adapter
Data is transferred from the data source to the data set and vice-versa through the Table Adapter
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12. DataSet w/Multiple Tables & Providers
1) Fill(DataSet, “TableX”)
SQL
Server
3) Return DataTable
SqlTableAdapter
DataSet
SelectCommand
2) Execute query
TableX
TableY
Oracle
OleDbTableAdapter
This slide shows multiple data sets with multiple data providers.
2 Types of Table Adapters:
SQL  Sql-Server
OleDB  Generic, including Access and Oracle
The data reader was forward only / read only access
The Data Set gives us FULL Power – forward / backwards, read / write capabilities
Object Oriented representation of the data source / database
Data Set – one or more data tables
A data table is like a data reader only with read / write access
It can be an actual table or the result of a query
A data set encapsulates the data tables into one named set
The Table Adapter’s Fill Method will fill (or create) the data table
The Table Adapter’s Command Object contains the Select Command
Connection to DB
Command to invoke query to build table (retrieve data from database and build the data table)
The DataSet / DataTable method uses more memory and is slightly slower than the data reader
You can create multiple data tables with the Table Adapter – Even from different data sources
6) Return DataTable
SelectCommand
5) Execute query
4) Fill(DataSet, “TableY”)
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13. TableAdapter Class
Provides communication between the application and database
Represents a set of data commands and a database connection that are used to fill the DataSet and update the data source based on queries
Can contain multiple queries – called like methods
Created with
Code
Dataset Designer
During Creation of a New Dataset – Data Source Configuration Wizard
Server Explorer / Dataset Designer
To Declare a TAble Adapter
Dim in Code OR Available in Design Window when creating, datasets
Command Properties:
Select
Insert
Update
Delete
These maybe too powerful, they build commands for you to interact with the database
Fill: Select command to retrieve data from the Database
Update: Saves the changes made to the Data Table and saves to the original data source (database)
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14. TableAdapter Class __Command properties (Created through Queries):
Select Query – Used in Fill Method
Insert Command, Update Command, Delete Command
Can be Created by default if enough information is available in the Select query (Fill Method)
Methods:
Fill – populated the Data Table with the result of the select command
Update – Sends changes back to the database
Insert – creates a new row in the data table
ClearBeforeFill – Clears the data table before executing a fill method
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15. TableAdapter: __Command Properties
Contain command objects to perform operations against the underlying database
Select Command
Populates a DataTable with the results of a query
Uses SQL SELECT statement typically
Insert Command
Inserts rows added to a DataTable into database
Uses SQL INSERT statement
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16. TableAdapter: __Command Properties (cont.)
Update
Writes changes made to a DataTable into the underlying database
Uses SQL UPDATE statement
Delete Command
Makes deletions of rows in a DataTable permanent by deleting those rows from the database
Uses SQL DELETE statement
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17. DataAdapter: Fill Method
Adds or refreshes rows in the DataSet to match those in the data source using the DataSet name
Creates a DataTable named "Table"
taEmployee.Fill(dsCompany.AllEmployees)
The fill method gives the DataTable a name
If a data table already exists with this name it will APPEND to it
Name for Data Table
Table Adapter
Method
Data Set
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18. TableAdapter: Update Method
Used to persist changes to a DataTable (i.e. save them in the database)
Calls the respective INSERT, UPDATE, or DELETE statements for each inserted, updated, or deleted row in the specified DataSet from a DataTable named "Table"
taEmployee.UpdateCommand(dsEmployee)
Stores the changes made in the data table in the original data source / database
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19. Table Adapter – Through IDE
Server Explorer
Click on Connect to DB Icon
Add Connection
Provide Data Source Type (Access, SQL Server)
Provide Database File
Test the Connection
Add DataSet
Data Menu  Add New Data Source
Project  Add New Item  DataSet
Select Items from Open Connection in Server Explorer
Creates the Data Set and Table Adapter
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20. Binding Source Data Aware Controls
Controls that can automatically display data from a table cell in the DataSet (most VB.net controls are data aware)
Controls must be Bound to the DataSet
DataBindings Property of Control
Arrow next to Text Field (of DataBindings)
Add or Select Data Source
Complete Data Source Configuration Wizard
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21. Currency Manager
Object that gives a way of navigating the rows of the DataTable. One row of the DataTable is always the current row
Data Aware controls display the data from the current row
Currency Manager objects are included in BindingSource components
Position Property  Number of the Current Row (zero based)
Count Property  How many rows are in the table
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22. Sample Code
Create a Visual Basic 2005 Application that will access the Baseball3 database and display the player information in bound textboxes. The program should use a Table Adapter, Data Set , Binding Source and Currency Manager to manipulate through the table data.
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23. Visual Studio.Net Wisdom
Update Command
TableAdapter.Update (Dataset.DataTable)
taEmployee.Fill(dsCompany.AllEmployees)
Updates the database
Updates the “local” copy in the Bin directory
Copied over by Visual Studio the next time the program is run
Don’t want you to corrupt your databases
How to accomplish a True Update?????
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24. Update Command Cannot use the IDE to develop your application
Must create the code by hand (Within Class Code)
Connection Object
DataAdapter Object
DataSet Object
DataTable Object
BindingSource Object
CommandBuilder Object
Import System.Data.OleDb (will be System.Data.SQL for SqlServer)
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25. Connection Object Create the connection to the data source
Uses the Connection String Information
Dim myConnection as New OleDb.Connection (connectionString)
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26. Data Adapter Object
Table Adapter is Not an Option Here, we must use a Data Adapter
Dim myDataAdapter as New OleDbDataAdapter (“sqlCommand”, connectionObject)
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27. Data Set Object Create the Data Set
Dim myDataSet as New DataSet (“DataSetName”)
Name of DataSet is a String, it must be in Quotation Marks
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28. Data Table Object Create the Data Table
Will Store the Data for the Data Set in Table form
Dim myDataTable as New DataTable (“DataTableName”)
Data Table Name is a string, it must be in Quotation Marks
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29. Binding Source
You must create a Binding Source Object to bind your data controls to the DataSet
Dim myBindingSource as New BindingSource
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30. Command Builder
Fill Command is automatically created for the Data Adapter Object
In an OleDb Connection a Command Builder object is needed to create the additional commands including Update
Dim myBuilder as New OldDbCommandBuilder (NameOfDataAdapterObject)
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31. Sample Code
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32. Form Load Event Open the Connection Add the DataTable to the DataSet
connectionObject.Open( )
Add the DataTable to the DataSet
dataSetObject.Tables.Add(dataTableObject)
Fill the DataSet through the DataAdapter
dataAdapterObject.Fill(dataSetObject, “StringName of DataTable”)
Bind the DataTable to the BindingSource
bindingSourceObject.DataSource = dataTableObject
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33. Form Load Events (Con’t)
Bind the Controls to the DataTable
Allows Bound Controls to Display Data from DataTable
controlName.DataBindings.Add (“text”, bindingSourceObject, “FieldName”)
“text” must be typed exactly as seen
“FieldName” is the name of the column from the Data Table – typically the name of the field in the Database (unless an alias is created by the SQL command)
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34. Sample Code
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35. BindingSource Object
BindingSource Object can manipulate through the DataTable
CurrencyManager is NOT Needed
BindingSource.Position
BindingSource.Count
BindingSource.MoveNext( )
BindingSource.MovePrevious( )
BindingSource.MoveFirst( )
BindingSource.MoveLast( )
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36. Finalizing Update EndEdit on the BindingSource Update the DataAdapter
Stops the Editing through the Binding Source
bindingSourceObject.EndEdit ( )
Update the DataAdapter
Send Changes back to Original Data Source
dataAdapterObject.Update (dataSetObject, “stringNameOfDataTable”)
Close the Connection
connectionObject.Close ( )
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37. DataGridView class The Windows Forms DataGridView control
Provides a user interface to ADO.NET datasets
displays tabular data
allows for updates to the data source
Data Grid gives a Tabular Representation of data in a database – DTG prefix
Value of a Data Grid – Users can view multiple rows and columns of data at one time, in a table (grid) format
- Column headings are assigned from the data source, can be overridden
- Scroll bars as necessary (best to show as much as possible in the window, especially important to show all columns)
- Show information that is IMPORTANT and MEANINGFUL to the user (you may need to store some data but not show it)
- User can modify data in the data grid and then update the database (update method from data adapter)
Be VERY careful with this – the USER control the actions, Verify Updates and Deletes
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38. Creating DataGridView Program
Connection Object
DataAdapter Object
DataSet Object
DataTable Object
CommandBuilder Object
No BindingSource object needed – Property of DataGridView
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39. Sample Code
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40. Binding the DataGrid
The DataGrid can receive data from any of the following data sources:
DataTable class
DataView class
DataSet class
DataViewManager class
dtgObject.DataSource=dataTable
dtgPlayer.DataSource = myPlayerTable
Working with the data grid
Connecting the the data source:
DataTable
DataView
DataSet (contains one or more data tables)
DataViewManager
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41. Binding the DataGridView
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42. Current row and cell Users can navigate on the DataGridViewer
CurrentRow.Index
Holds zero-based integer for highlighted row
CurrentCell property
Gets or sets which cell has the focus
Contains DataGridViewCell object
Has ColumnNumber and RowNumber properties
Item property holds cell content
‘* display cell contents of third column
Console.WriteLine(dtgTeam.Item(dtgTeam.CurrentRowIndex, 2))
To Access the Current Cell / Row (the one selected by the user)
Zero Based Integer
CurrentRowIndex
CurrentCell (has the focus)
ColumnNumber
RowNumber
Item Collection – holds the cell content
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43. Data in DataGridViewer
Read Only
dtgObject.ReadOnly = True
Storing a column in the DataGridView that you don’t want users to see (eg. Primary key field)
dtgObject.Columns(index).Visible = False
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44. Data Grid Example - Homework
Use Baseball Database (Baseball3.mdb)
DataGridView Example
Create Form with DataGridView Object
Create Needed Objects (in Code)
Hidden Column (Primary Key)
TeamID Column – Read Only
Update Database on Exit Button
Bonus: User OpenFileDialog box to Select Database
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