Coding ADO.Net DataSet Objects
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Transcript of Coding ADO.Net DataSet Objects
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(); }