Web Server Programming. Direct Data Access, Data Binding. Content. Direct Data Access Data Binding. Direct Data Access. Important Note!!!. Last week, you learned how to connect to databases using built-in controls. Use them in your applications whenever possible. - PowerPoint PPT Presentation
Web Server Programming
Web Server ProgrammingDirect Data Access, Data
BindingContentDirect Data AccessData BindingMuzaffer DOAN - Anadolu
University2Direct Data AccessMuzaffer DOAN - Anadolu
University3Important Note!!!Last week, you learned how to connect
to databases using built-in controls.Use them in your applications
whenever possible.If you sure that you need to connect to database
manually, follow the instructions explained in this class.Muzaffer
DOAN - Anadolu University4Direct Data Access QueryingCreate
Connection, Command, and DataReader objectsUse the DataReader to
retrieve information from the database, and display it in a
controlClose your connectionSend the page to the userMuzaffer DOAN
- Anadolu University5Updating, Inserting, DeletingCreate new
Connection and Command objectsExecute the Command with the
appropriate SQL statementMuzaffer DOAN - Anadolu University6Direct
Data Access with ADO.NETMuzaffer DOAN - Anadolu University7
ADO.NET Data Provider ClassesSQL ServerOleDB
(Access)ConnectionSqlConnectionOleDbConnectionCommandSqlCommandOleDbCommandDataReaderSqlDataReaderOleDbDataReaderDataAdapterSqlDataAdapterOleDbDataAdapterMuzaffer
DOAN - Anadolu University8Use OracleConnection, OracleCommand, etc.
for Oracle data providersUse OdbcConnection, OdbcCommand, etc. for
ODBC data providersNamespace ImportsImport following namespaces for
SQL Server:using System.Data;using System.Data.SqlClient;Import
following namespaces for Access:using System.Data;using
System.OleDb;Muzaffer DOAN - Anadolu University9Connecting Access
DatabaseOleDbConnection conn = new OleDbConnection();
conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data
Source=|DataDirectory|\Survey.mdb";
conn.Open();
// Database operations will be here...
conn.Close();Muzaffer DOAN - Anadolu University10Connecting SQL
Server ExpressSqlConnection conn = new SqlConnection();
conn.ConnectionString = @"Data Source=.\SQLEXPRESS;
AttachDbFilename=|DataDirectory|\Survey.mdf; Integrated
Security=True;User Instance=True";
conn.Open();
// Database operations will be here...
conn.Close();Muzaffer DOAN - Anadolu University11How to Obtain
Connection StringsUse SqlDataSource or AccessDataSource objects to
connect to the database and copy the connection strings into your
codehttp://www.connectionstrings.com shows many connection string
optionsMuzaffer DOAN - Anadolu University12Storing the Connection
StringWrite the connection string into connectionString section of
web.config file:
...
Muzaffer DOAN - Anadolu University13Retrieving the Connection
Stringstring connectionString =
WebConfigurationManager.ConnectionStrings["Pubs"].ConnectionString;Muzaffer
DOAN - Anadolu University14Execute CommandCommand object has
several methods starting with the "Execute"
string:ExecuteNonQuery(): Used for queries that don't return any
records (e.g. Update, Insert, Delete queries)ExecuteReader(): Used
for queries that return one or more records (e.g. Select
query)ExecuteScalar(): Used for queries that return one or more
records but this method returns only the first column of the first
row (suitable for obtaining number of records, maximum value of a
column)Muzaffer DOAN - Anadolu University15The DataReaderAllows you
to quickly retrieve all your resultsUses a live connection and
should be used quickly and then closedCan retrieve only one record
at a timeSupports fast-forward-only and read-only access to the
results (previous record cannot be reached)Provides better
performance than the DataSetMuzaffer DOAN - Anadolu University16The
DataReaderCreate a DataReader by ExecuteReader method of the
Command objectRetrieve the record by the Read() method of the
DataReader objectTo retrieve the next record, use Read() method
againIf next record is successfully read, the Read() method returns
trueSo, continue reading until the Read() method returns
falseMuzaffer DOAN - Anadolu University17The
DataReaderOleDbConnection conn = new
OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data
Source=|DataDirectory|\Survey.mdb");OleDbCommand cmd = new
OleDbCommand("SELECT * FROM UserInfo",
conn);conn.Open();OleDbDataReader reader =
cmd.ExecuteReader();while (reader.Read()){ Label1.Text +=
reader["FirstName"] + "
";}reader.Close();conn.Close();Muzaffer DOAN - Anadolu
University18ExecuteScalar ExampleOleDbConnection conn = new
OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data
Source=|DataDirectory|\Survey.mdb");OleDbCommand cmd = new
OleDbCommand("SELECT MAX(FavoriteNumber) FROM UserInfo",
conn);conn.Open();
int maxfav = (int)cmd.ExecuteScalar();
conn.Close();Muzaffer DOAN - Anadolu University19ExecuteNonQuery
ExampleOleDbConnection conn = new
OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data
Source=|DataDirectory|\Survey.mdb");OleDbCommand cmd = new
OleDbCommand("DELETE * FROM UserInfo WHERE UserID=5",
conn);conn.Open();
int affectedRowNumber = cmd.ExecuteNonQuery();
conn.Close();Muzaffer DOAN - Anadolu University20Data
BindingMuzaffer DOAN - Anadolu University21Data BindingYou can use
the DataSet or the DataReader to retrieve rows of information,
format them individually, and add them to an HTML table on a web
pageConceptually, this isnt too difficult. However, it still
requires a lot of repetitive code to move through the data, format
columns, and display it in the correct orderRepetitive code may be
easy, but its also error-prone, difficult to enhance, and
unpleasant to readFortunately, ASP.NET adds a feature that allows
you to skip this process and pop data directly into HTML elements
and fully formatted controls. Its called data bindingMuzaffer DOAN
- Anadolu University22Data BindingThe basic principle of data
binding is this: you tell a control where to find your data and how
you want it displayed, and the control handles the rest of the
details.ASP.NET data binding works in one direction only.
Information moves from a data object into a control. Then the data
objects are thrown away, and the page is sent to the client. If the
user modifies the data in a data-bound control, your program can
update the corresponding record in the database, but nothing
happens automatically.Muzaffer DOAN - Anadolu University23Types of
ASP.NET Data BindingSingle-Value, or "Simple", Data
BindingSingle-value data binding allows you to take a variable, a
property, or an expression and insert it dynamically into a
pageSingle-value binding also helps you create templates for the
rich data controlsRepeated-Value, or "List", BindingAllows you to
display an entire table (or just a single field from a
table)Muzaffer DOAN - Anadolu University24Using Data BindingTo use
single-value binding, you must insert a data binding expression
into the markup in the .aspx file (not the code-behind file).To use
repeated-value binding, you must set one or more properties of a
data control.Once you specify data binding, you need to activate
it. You accomplish this task by calling the DataBind() method of
the control.Alternatively, you can bind the whole page at once by
calling the DataBind() method of the current Page object.Muzaffer
DOAN - Anadolu University25A Simple List Binding ExampleArrayList
fruit = new
ArrayList();fruit.Add("Kiwi");fruit.Add("Mango");fruit.Add("Blueberry");fruit.Add("Apricot");fruit.Add("Banana");lstItems.DataSource
= fruit;lstItems.DataBind(); // orthis.DataBind();Muzaffer DOAN -
Anadolu University26ReferencesBeginning ASP.NET 3.5 in C# 2008:
From Novice to ProfessionalVisual Studio and MSDN HelpMuzaffer DOAN
- Anadolu University27
