Coding ADO.Net DataSet Objects

DataSet Object

• A DataSet object can hold several tables and relationships between tables.

• A DataSet is a set of disconnedted data. Data is extracted from the database and stored in the DataSet object. Updates to the DataSet must copy back to the database to make the changes permanent.

DataSet and Related Objects• DataSet: Can contain multiple tables and

relationships.• DataTable object: Represents a table in the

dataset.• DataAdapter: This the object used to pass

data between the database and the dataset. The Fill method copies the data into the dataset, and the Update method copies the updates back into the database.

• DataView: This represents a specific view of the DataTables held in the dataset.

DataSet and Related Objects

DataSet

Tables

DataAdapter

Commands

Connection

DataView

DataSource

Structure of a Dataset

Dataset

Tables

Data table

Rows

Data Row

Columns

Data Column

Constraints

ConstraintRelations

Data Relation

Reading Data into a Table

• string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";

• OleDbConnection objConn = new OleDbConnection(strConn);• DataSet objDataSet = new DataSet();• string strSQL= "select * from customer;";• OleDbDataAdapter objAdapter=new OleDbDataAdapter(strSQL,

objConn);• objAdapter.Fill(objDataSet, "Customer");

Binding DataGridView with Codeprivate void Form6_Load(object sender, EventArgs e)

{

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";

OleDbConnection objConn = new OleDbConnection(strConn);

DataSet objDataSet = new DataSet();

string strSQL= "select * from customer;";

OleDbDataAdapter objAdapter=new OleDbDataAdapter(strSQL, objConn);

objAdapter.Fill(objDataSet, "Customer");

dataGridView1.DataSource = objDataSet;

dataGridView1.DataMember = "Customer";

}

Note: Adapter’s Fill method is able to open the connection.

Binding a ListBox with Codeprivate void Form7_Load(object sender, EventArgs e)

{

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";

OleDbConnection objConn = new OleDbConnection(strConn);

DataSet objDataSet = new DataSet();

string strSQL = "select * from customer;";

OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn);

objAdapter.Fill(objDataSet, "Customer");

listBox1.DataSource = objDataSet.Tables["customer"];

listBox1.DisplayMember = "CID";

listBox1.ValueMember = "Cname";

}

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)

{

textBox1.Text = listBox1.SelectedValue.ToString();

}

Note: How to access other fields?

Navigate a dataset to access a column of a row in a table

• DataSet: has a collection of tables– Tables: each member is a DataTable object

• Table: has a collection of rows– Rows: each member is a DataRow object

» Row: has a collection of fields

• Example: the Rating field of the first row of the Customer table:– objDataSet.Tables["customer"].Rows[0]

["Rating"].ToString();

Binding a ListBox and display selected record in textboxes DataSet objDataSet = new DataSet();

private void Form7_Load(object sender, EventArgs e)

{

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";

OleDbConnection objConn = new OleDbConnection(strConn);

string strSQL = "select * from customer;";

OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn);

objAdapter.Fill(objDataSet, "Customer");

listBox1.DataSource = objDataSet.Tables["customer"];

listBox1.DisplayMember = "CID";

listBox1.ValueMember = "Cname";

}

private void listBox1_SelectedIndexChanged(object sender, EventArgs e)

{

textBox1.Text = listBox1.SelectedValue.ToString();

textBox2.Text = objDataSet.Tables["customer"].Rows[listBox1.SelectedIndex]["Rating"].ToString();

}

Note: Different from previous example, objDataSet is defined as a form level object. Why?

Navigate Records in a TableDataSet objDataSet = new DataSet(); int rowIndex = 0; private void Form8_Load(object sender, EventArgs e) { string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb"; OleDbConnection objConn = new OleDbConnection(strConn); string strSQL = "select * from customer;"; OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn); objAdapter.Fill(objDataSet, "Customer"); textBox1.Text = objDataSet.Tables["customer"].Rows[rowIndex]["cid"].ToString(); textBox2.Text = objDataSet.Tables["customer"].Rows[rowIndex]["cname"].ToString(); textBox3.Text = objDataSet.Tables["customer"].Rows[rowIndex]["city"].ToString(); }

private void button1_Click(object sender, EventArgs e) { rowIndex += 1; if (rowIndex > objDataSet.Tables["customer"].Rows.Count - 1) rowIndex = objDataSet.Tables["customer"].Rows.Count - 1; textBox1.Text = objDataSet.Tables["customer"].Rows[rowIndex]["cid"].ToString(); textBox2.Text = objDataSet.Tables["customer"].Rows[rowIndex]["cname"].ToString(); textBox3.Text = objDataSet.Tables["customer"].Rows[rowIndex]["city"].ToString(); }

private void button2_Click(object sender, EventArgs e) { rowIndex -= 1; if (rowIndex <0) rowIndex = 0; textBox1.Text = objDataSet.Tables["customer"].Rows[rowIndex]["cid"].ToString(); textBox2.Text = objDataSet.Tables["customer"].Rows[rowIndex]["cname"].ToString(); textBox3.Text = objDataSet.Tables["customer"].Rows[rowIndex]["city"].ToString(); }

Move Next and Move Previous Procedures

Use foreach loop to access records in table’s Rows Collection

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";OleDbConnection objConn = new OleDbConnection(strConn);string strSQL = "select * from customer;";OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn);DataSet objDataSet = new DataSet();objAdapter.Fill(objDataSet, "Customer");string strOutput="";foreach (DataRow objRow in objDataSet.Tables["customer"].Rows) strOutput = strOutput+ objRow["cid"].ToString() + objRow["cname"].ToString() + objRow["city"].ToString() + Environment.NewLine;textBox1.Text = strOutput.ToString();

DataView ObjectConvenient for Binding and Display Records Meeting

Criteria

• The DataView object exposes a complete table or a subset of the records from a table.

• To create a DataView, use a Table’s DefaultView property:– DataView objDataView = new DataView();– objDataView = objDataSet.Tables["customer"].DefaultView;

• DataView can be used as a DataSource in data binding.

• Other useful methods:– Find, Sort

Data Binding with DataView Object

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data

Source=C:\\SalesDB2011.accdb";OleDbConnection objConn = new OleDbConnection(strConn);string strSQL = "select * from customer;";OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn);DataSet objDataSet = new DataSet();objAdapter.Fill(objDataSet, "Customer");DataView objDataView = new DataView();objDataView = objDataSet.Tables["customer"].DefaultView;

dataGridView1.DataSource = objDataView;

Selecting a Subset of Records with DataView’s RowFilter Property

• objDataView.RowFilter = criteria;• Criteria is a string of condition• Examples of criteria:

– “Rating=‘A’”– “City = ‘SF’”

• The criteria can be complex condition. Use logical operators AND, OR to write a complex condition.

• Examples of complex condition:– “City = ‘SF’ AND Rating=‘A’”– "Rating='A' and City='SF' or rating='C'"

Example: Display customers with the selected rating

DataView Example private void radioButton1_CheckedChanged(object sender, EventArgs e)

{

if (radioButton1.Checked)

objDataView.RowFilter = "Rating='A'";

else if (radioButton2.Checked)

objDataView.RowFilter = "Rating='B'";

else

objDataView.RowFilter = "Rating='C'";

dataGridView1.DataSource = objDataView;

}

DataView with Sort

objDataView.Sort = "Cname";dataGridView1.DataSource = objDataView;

Creating multiple tables: One Adapter, One Table

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";OleDbConnection objConn = new OleDbConnection(strConn);string strSQL = "select * from customer;";OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn);DataSet objDataSet = new DataSet();objAdapter.Fill(objDataSet, "Customer");string strSQL2 = "select * from orders;";OleDbDataAdapter objAdapter2 = new OleDbDataAdapter(strSQL2, objConn);objAdapter2.Fill(objDataSet, "orders");

Creating Multiple Tables: One Adapter, Many Tables

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";OleDbConnection objConn = new OleDbConnection(strConn);string strSQL = "select * from customer;";OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn);DataSet objDataSet = new DataSet();objAdapter.Fill(objDataSet, "Customer");string strSQL2 = "select * from orders;";objAdapter.SelectCommand.CommandText = strSQL2;objAdapter.Fill(objDataSet, "orders");

Adding Relationship to a Dataset

• The Dataset object has a Relations property. It is a collection of DataRelations. We can use a relationship to enforce the referential integrity.

• To define a DataRelation:– DataRelObj=DataRelation(RelationName,

ParentTable Field, ChildTableField)• DataRelation objRel;

• objRel = new DataRelation("custOrder", objDataSet.Tables["Customer"].Columns["cid"], objDataSet.Tables["orders"].Columns["cid"]);

• Adding a relation to the dataset:– objDataSet.Relations.Add(objRel);

Code to Define and Add a Relation

DataRelation objRel;

objRel = new DataRelation("custOrder", objDataSet.Tables["Customer"].Columns["cid"], objDataSet.Tables["orders"].Columns["cid"]);

objDataSet.Relations.Add(objRel);

Creating a Parent/Child Form

Binding Textbox and Binding GridView to a Relation

textBox1.DataBindings.Add("text", objDataSet, "customer.cid");textBox2.DataBindings.Add("text", objDataSet, "customer.cname");dataGridView1.DataSource = objDataSet;dataGridView1.DataMember = "Customer.custOrder";

Parent/Child FormDataSet objDataSet = new DataSet(); private void Form11_Load(object sender, EventArgs e) { string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb"; OleDbConnection objConn = new OleDbConnection(strConn); string strSQL = "select * from customer;"; OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn); objAdapter.Fill(objDataSet, "Customer"); string strSQL2 = "select * from orders;"; objAdapter.SelectCommand.CommandText = strSQL2; objAdapter.Fill(objDataSet, "orders"); DataRelation objRel; objRel = new DataRelation("custOrder", objDataSet.Tables["Customer"].Columns["cid"], objDataSet.Tables["orders"].Columns["cid"]); objDataSet.Relations.Add(objRel); textBox1.DataBindings.Add("text", objDataSet, "customer.cid"); textBox2.DataBindings.Add("text", objDataSet, "customer.cname"); dataGridView1.DataSource = objDataSet; dataGridView1.DataMember = "Customer.custOrder"; } private void button1_Click(object sender, EventArgs e) { this.BindingContext[objDataSet, "Customer"].Position += 1; } private void button2_Click(object sender, EventArgs e) { this.BindingContext[objDataSet, "Customer"].Position -= 1; }

Parent/Child Form without a Relation

• This form lets users to select a CID from a listbox, then displays parent information in textboxes and child records in a datagrid by defining a dataview on Orders table based on selected CID.

– Use View’s FilterDataView objDataView = new DataView();

objDataView = objDataSet.Tables["orders"].DefaultView;

objDataView.RowFilter = "CID='" + listBox1.SelectedValue.ToString() + "'";

dataGridView1.DataSource = objDataView;

Parent/Child form with Listbox

DataSet objDataSet = new DataSet(); private void Form12_Load(object sender, EventArgs e) { string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb"; OleDbConnection objConn = new OleDbConnection(strConn); string strSQL = "select * from customer;"; OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn); objAdapter.Fill(objDataSet, "Customer"); string strSQL2 = "select * from orders;"; objAdapter.SelectCommand.CommandText = strSQL2; objAdapter.Fill(objDataSet, "orders"); listBox1.DataSource=objDataSet.Tables["Customer"]; listBox1.DisplayMember = "CID"; listBox1.ValueMember = "CID"; } private void listBox1_SelectedIndexChanged(object sender, EventArgs e) { textBox1.Text = objDataSet.Tables["customer"].Rows[listBox1.SelectedIndex]["Cname"].ToString(); textBox2.Text = objDataSet.Tables["customer"].Rows[listBox1.SelectedIndex]["Rating"].ToString(); DataView objDataView = new DataView(); objDataView = objDataSet.Tables["orders"].DefaultView; objDataView.RowFilter = "CID='" + listBox1.SelectedValue.ToString() + "'"; dataGridView1.DataSource = objDataView; }

Save a Copy of DataSet - DataSet.WriteXml

string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb";OleDbConnection objConn = new OleDbConnection(strConn);string strSQL = "select * from customer;";OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn);objAdapter.Fill(objDataSet, "Customer");string strSQL2 = "select * from orders;";objAdapter.SelectCommand.CommandText = strSQL2;DataSet objDataSet = new DataSet();objAdapter.Fill(objDataSet, "orders");objDataSet.WriteXml("C:\\CustOrderDS.xml");

ReadXML

DataSet objDataSet=new DataSet(); objDataSet.ReadXml("c:\\CustOrderDS.xml"); dataGridView1.DataSource = objDataSet; dataGridView1.DataMember = "Customer";

Using BindingSouce for navigationDataSet objDataSet = new DataSet(); BindingSource objBS = new BindingSource(); private void Form9_Load(object sender, EventArgs e) { string strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\SalesDB2011.accdb"; OleDbConnection objConn = new OleDbConnection(strConn); string strSQL = "select * from customer;"; OleDbDataAdapter objAdapter = new OleDbDataAdapter(strSQL, objConn); objAdapter.Fill(objDataSet, "Customer"); objBS.DataSource = objDataSet; objBS.DataMember = "Customer"; textBox1.DataBindings.Add("text", objBS, "CID"); textBox2.DataBindings.Add("text", objBS, "Cname"); } private void button1_Click(object sender, EventArgs e) { objBS.MoveNext(); }

private void button2_Click(object sender, EventArgs e) { objBS.MovePrevious(); }