ByRadhika Malladi

IntroductionADO.Net : database API, used for managed

applications

It consists of a set of classesIntegrates with XMLIt provides components for creating

distributed, data-sharing applicationsIt is used to connect to data source for

retrieving, updating and manipulating data.

Data providers are used to connect to the database, to execute commands and retrieving results

ADO.Net provides two data providers

SQL Server .Net provider – Interfaces MicrosoftSQLServer with Managed applications(System.data.SqlClient)

OLE DB .Net provider – Interfaces databases with UnManaged OLE DB providers(System.data.OleDb)

Introduction cont.

ADO.Net is designed to meet the following goals:

1. Leverage current ADO knowledge2. Support N-tier programming model

("Any number of levels arranged above another, each serving distinct and separate tasks.“)

Done by using Data Set because Data Set works well with all providers

3. Integrating XML

Design Goals

Two main components:

1. Data Set – disconnected architecture of ADO.Net

2. .Net data provider components – for data manipulation and read-only access to dataConnection – to make connections to databaseCommand – access to database commandsData Reader – provides stream of data from data sourceData Adapter – bridge between Data Set object and

data source

ADO.Net Components

Architecture

Connection :SqlConnection conn = new SqlConnection

    ("server=localhost;database=a1;uid=sa;pwd=");

SqlConnection conn = new SqlConnection     ("server=xyz\malladi;database=a1;uid=sa;pwd=");

SqlConnection conn = new SqlConnection     ("server=xyz\malladi;database=a1;uid=sa;pwd=;min pool size=10;max pool size=50;connect timeout=10;Integrated Security = false;Pooling = true;");

OleDbConnection conn = new OleDbConnection     ("provider=sqloledb;data source=localhost;OLE DB Services=-2" +    

"initial catalog=a1;user id=sa;password=");

.Net provider Components

Command:SqlCommand cmd = new SqlCommand ("select * from users", conn);

Properties: CommadTimeout , CommandText

Methods:ExecuteNonQuery() – This returns number of rows affected

Ex: Insert, Delete, Update (no return values)

ExecuteScalar() – single row, single column valuesEx: count, min, max, sum, avg etc and to retrive BLOBs

ExecuteReader()

.Net Components cont.

Data Reader:

SqlDataReader reader = cmd.ExecuteReader ();

ExecuteReader() – obtains query results quickly for read-only.Ex: Select

reader.close();

Methods:GetName – retrieve field namesGetValue – retrieve field values(returns obj)GetOrdinal – converts field name into numeric index

.Net Components cont.

Data Adapter:

SqlDataAdapter adapter = new SqlDataAdapter ("select * from users",     "server=localhost;database=a1;uid=sa;pwd=");

.Net Components cont.

SqlConnection con = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=C:\\Inetpub\\wwwroot\\Assign2\\App_Data\\a2.mdf;Integrated Security=True;User Instance=True");

try { con.Open(); SqlCommand cmd = new SqlCommand("select role from users where username = '" +

TextBox1.Text.Trim() + "' and password = '" + TextBox2.Text.Trim() + "'", con); SqlDataReader dr = cmd.ExecuteReader(); while (dr.Read()) { role = dr.GetString(dr.GetOrdinal("role")); break; } } catch (SqlException ex) { Response.Write(ex.Message); } finally { con.Close(); }

Example (ExecuteReader)

SqlConnection connection = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=c:\\inetpub\\wwwroot\\Assign2\\App_Data\\a2.mdf;Integrated Security=True;User Instance=True");

try{ connection.Open(); StringBuilder builder = new StringBuilder(); builder.Append("select count (*) from users where username = \'"); builder.Append(username); builder.Append("\' and cast (rtrim (password) as varbinary) = cast (\'"); builder.Append(password); builder.Append("\' as varbinary)"); SqlCommand command = new SqlCommand(builder.ToString(),connection); int count = (int)command.ExecuteScalar(); return (count > 0); } catch (SqlException) { return false; } finally { connection.Close(); }

Example (ExecuteScalar)

SqlConnection con = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=C:\\Inetpub\\wwwroot\\Assign2\\App_Data\\a2.mdf;Integrated Security=True;User Instance=True");

try { con.Open(); SqlCommand cmd = new SqlCommand("insert into users

(username,password,role)values('" + TextBox6.Text.Trim() + "','" + TextBox7.Text.Trim() + "','" + DropDownList1.SelectedValue + "')", con);

int noofrows = cmd.ExecuteNonQuery(); if (noofrows != 0) Response.Write("user created successfully"); } catch (SqlException ex) { Response.Write(ex.Message); } finally { con.Close(); }

Example (ExecuteNonQuery)

Set based access – captures query into memory and supports traversal through result set

This has 2 classesData Set : in-memory databaseData Adapter : bridge between Data Set and

data sourcePerform database queries create DataTables containing query resultsCapable of writing changes made to data tables back

to database

Data Set and Data Adapters

Two versions: SqlDataAdapter and OleDbDataAdapter

Main Methods of Data Adapter are Fill and Update

Namespace – system.data.common.DbDataAdapter

Data Adapter

Fill:

SqlDataAdapter adapter = new SqlDataAdapter ("select * from users",     "server=localhost;database=a1;uid=sa;pwd="); DataSet ds = new DataSet ();

adapter.Fill (ds, “users");

Update :adapter.Update (table);

Builder for Insert, Update, Delete:SqlCommandBuilder builder = new SqlCommandBuilder (adapter);

Data Adapter cont.

DataSet object – supports disconnected, distributed data with ADO.Net

Can be used with multiple and differing data sources

It represents complete set of data like related tables, constraints and relationships among tables

Data Set

Data Set cont.

DataTable Collection : contains collection of tables

DataRelationCollection: contains relationships of tables

ExtendingProperties: Property Collection where customized information can be placedEx: Date/Time when data is generated

Data Set cont.

SqlDataAdapter adapter = new SqlDataAdapter ("select * from titles",     "server=localhost;database=pubs;uid=sa;pwd=");

DataSet ds = new DataSet (); adapter.Fill (ds, "Titles"); // Create a new DataRow DataTable table = ds.Tables["Titles"]; DataRow row = table.NewRow (); // Initialize the DataRow row["title_id"] = "JP1001"; row["title"] = "Programming Microsoft .NET"; row["price"] = "59.99"; row["ytd_sales"] = "1000000"; row["type"] = "business"; row["pubdate"] = "May 2002"; // Add the DataRow to the DataTable table.Rows.Add (row);

Example to insert records

DataRow[] rows = table.Select ("title_id = 'JP1001'");DataRow[] rows = table.Select ("price < 10.00");DataRow[] rows = table.Select ("pubdate >= '#1/1/2000#'"

);DataRow[] rows = table.Select ("state in ('ca', 'tn', 'wa')"); DataRow[] rows = table.Select ("state like 'ca*'");DataRow[] rows = table.Select ("isnull (state, 0) = 0");DataRow[] rows = table.Select ("state = 'tn' and zip like '37

*'");

Examples to select records

SqlDataAdapter adapter = new SqlDataAdapter ("select * from titles",     "server=localhost;database=pubs;uid=sa;pwd=");

DataSet ds = new DataSet (); adapter.Fill (ds, "Titles");DataRow[] rows = table.Select ("ytd_sales > 10000");foreach (DataRow row in rows)     row["price"] = (decimal) row["price"] + 10.00m;

Example to update records

SqlDataAdapter adapter = new SqlDataAdapter ("select * from titles",     "server=localhost;database=pubs;uid=sa;pwd=");

DataSet ds = new DataSet (); adapter.Fill (ds, "Titles"); DataRow[] rows =     table.Select 

("ytd_sales < 10000 OR isnull (ytd_sales, 0) = 0"); foreach (DataRow row in rows)     row.Delete ();

Example to delete records

SqlDataAdapter adapter =     new SqlDataAdapter ("select * from titles",     "server=localhost;database=pubs;uid=sa;pwd=");

SqlCommandBuilder builder = new SqlCommandBuilder (adapter); DataSet ds = new DataSet (); adapter.Fill (ds, "Titles"); // Insert a record DataTable table = ds.Tables["Titles"]; DataRow row = table.NewRow (); row["title_id"] = "JP1001"; row["title"] = "Programming Microsoft .NET"; row["price"] = 59.99m; row["ytd_sales"] = 1000000; row["type"] = "business"; row["pubdate"] = new DateTime (2002, 5, 1); table.Rows.Add (row); // Update the database adapter.Update (table);

Example for Updating the database

User defined command added to a database

Executes faster as they are already complied

Improves performance

ADO.Net supports stored procedures

An Example of stored procedure is..

Stored Procedures

CREATE PROCEDURE proc_TransferFunds     @Amount money,     @From char (10),     @To char (10) AS     BEGIN TRANSACTION   UPDATE Accounts SET Balance = Balance @Amount  

WHERE Account_ID = @From     IF @@ROWCOUNT = 0     BEGIN         ROLLBACK TRANSACTION         RETURN   END    UPDATE Accounts SET Balance = Balance + @Amount         WHERE Account_ID = @To     IF @@ROWCOUNT = 0     BEGIN         ROLLBACK TRANSACTION         RETURN     END     COMMIT TRANSACTION GO

SqlConnection conn = new SqlConnection     ("server=localhost;database=mybank;uid=sa;pwd="); try {     

conn.Open ();   

  SqlCommand cmd = new SqlCommand ("proc_TransferFunds", conn);

    cmd.CommandType = CommandType.StoredProcedure;      cmd.Parameters.Add ("@amount", 1000);     cmd.Parameters.Add ("@from", 1111);      cmd.Parameters.Add ("@to", 2222);     cmd.ExecuteNonQuery (); }

catch (SqlException ex) {     // TODO: Handle the exception }

finally {     conn.Close (); }

SqlConnection conn = new SqlConnection     ("server=localhost;database=mybank;uid=sa;pwd=");

try {     conn.Open ();     // Debit $1,000 from account 1111     SqlCommand cmd = new SqlCommand

 ("update accounts set balance = balance -1000 where account_id = '1111'", conn);    

 cmd.ExecuteNonQuery ();     // Credit $1,000 to account 2222     cmd.CommandText = "update accounts set balance = " +        

"balance + 1000 where account_id = '2222'";     cmd.ExecuteNonQuery (); } catch (SqlException ex) {     // TODO: Handle the exception } finally {     conn.Close (); }

Transacted Commands Example

SqlTransaction trans = null; SqlConnection conn = new SqlConnection     ("server=localhost;database=mybank;uid=sa;pwd="); try {     conn.Open ();

    // Start a local transaction     trans = conn.BeginTransaction (IsolationLevel.Serializable);     // Create and initialize a SqlCommand object     SqlCommand cmd = new SqlCommand ();     cmd.Connection = conn;     cmd.Transaction = trans;     // Debit $1,000 from account 1111     cmd.CommandText = "update accounts set balance =

balance - 1000 where account_id = '1111'";     cmd.ExecuteNonQuery ();     // Credit $1,000 to account 2222     cmd.CommandText = "update accounts set balance = " +        

"balance + 1000 where account_id = '2222'";     cmd.ExecuteNonQuery ();     // Commit the transaction (commit changes)     trans.Commit (); } catch (SqlException) {     // Abort the transaction (roll back changes)  if (trans != null)

trans.Rollback (); } finally {     conn.Close (); }

Transacted Commands Example

SqlConnection conn = new SqlConnection     ("server=localhost;database=mybank;uid=sa;pwd=");

try { conn.Open ();     // Create and initialize a SqlCommand object     SqlCommand cmd = new SqlCommand("update accounts set balance = bala

nce + @amount " +         "where account_id = @id", conn);     cmd.Parameters.Add ("@amount", SqlDbType.Money);     cmd.Parameters.Add ("@id", SqlDbType.Char);     // Debit $1,000 from account 1111     cmd.Parameters["@amount"].Value = -1000;     cmd.Parameters["@id"].Value = "1111";     cmd.ExecuteNonQuery ();     // Credit $1,000 to account 2222     cmd.Parameters["@amount"].Value = 1000;     cmd.Parameters["@id"].Value = "2222";     cmd.ExecuteNonQuery (); } catch (SqlException ex) {     // TODO: Handle the exception } finally {     conn.Close (); }

Parameterized Commands Example

ADO.Net by Alex HomerProgramming Microsoft .Net by Jeff

Prosisehttp://msdn2.microsoft.com/en-us/library/

e80y5yhx(VS.71).aspxhttp://www.ondotnet.com/pub/a/dotnet/ex

cerpt/progvisbasic_ch08/index.html

References

Thank youThank you