🔗 ASP.NET Data Handling & Integration – Database Access, ADO.NET, LINQ & Binding

🧲 Introduction – Powering Dynamic Web Apps with Data in ASP.NET

Every dynamic web application needs to interact with a database or data source. ASP.NET simplifies this process with technologies like ADO.NET, data binding controls, and LINQ, enabling fast and reliable CRUD operations, live UI updates, and seamless database integration.

🎯 In this guide, you’ll learn:

• How to connect ASP.NET to databases using ADO.NET
• How to use data sources in web forms
• How to bind data to UI controls
• How to integrate LINQ for simplified querying
• Best practices for secure and efficient data access

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📘 Topics Covered

🔹 Topic	📖 Description
🗄️ Database Access	Connect to SQL Server and other databases
🔗 ADO.NET in ASP.NET	Use SqlConnection, SqlCommand, and SqlDataAdapter for CRUD
📥 Data Sources	Use declarative controls like SqlDataSource, ObjectDataSource
🧶 Data Binding	Bind data to GridView, ListView, DropDownList, etc.
📊 LINQ Integration	Query data collections and databases using LINQ syntax

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🗄️ ASP.NET – Database Access

🔹 SQL Server Connection Example

string connStr = "Server=.;Database=MyDB;Trusted_Connection=True;";
SqlConnection conn = new SqlConnection(connStr);
conn.Open();

✅ Use parameterized queries to prevent SQL injection:

SqlCommand cmd = new SqlCommand("SELECT * FROM Users WHERE Id=@id", conn);
cmd.Parameters.AddWithValue("@id", 1);

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🔗 ASP.NET – ADO.NET

ADO.NET is the foundational data access API in ASP.NET.

🔹 Perform SELECT

SqlCommand cmd = new SqlCommand("SELECT Name FROM Users", conn);
SqlDataReader reader = cmd.ExecuteReader();

while(reader.Read()) {
    string name = reader["Name"].ToString();
}

🔹 INSERT / UPDATE

SqlCommand cmd = new SqlCommand("INSERT INTO Users (Name) VALUES (@name)", conn);
cmd.Parameters.AddWithValue("@name", "Alice");
cmd.ExecuteNonQuery();

✅ Use SqlDataAdapter + DataSet for disconnected data access.

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📥 ASP.NET – Data Sources

Declarative data access for Web Forms:

<asp:SqlDataSource 
    ID="SqlDataSource1" 
    runat="server" 
    ConnectionString="<%$ ConnectionStrings:MyConn %>"
    SelectCommand="SELECT * FROM Users">
</asp:SqlDataSource>

<asp:GridView 
    ID="GridView1" 
    runat="server" 
    DataSourceID="SqlDataSource1" 
    AutoGenerateColumns="True">
</asp:GridView>

✅ Other sources:

• ObjectDataSource: Calls methods in C# classes
• XmlDataSource: Binds XML documents
• AccessDataSource: Reads .mdb files

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🧶 ASP.NET – Data Binding

🔹 One-Way Binding (Code-Behind)

GridView1.DataSource = myDataTable;
GridView1.DataBind();

✅ Controls that support binding:

• GridView
• DetailsView
• DropDownList
• Repeater

🔹 Two-Way Binding with Templates

<ItemTemplate>
    <asp:TextBox ID="txtName" runat="server" Text='<%# Bind("Name") %>' />
</ItemTemplate>

✅ Enables inline editing and updates.

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📊 ASP.NET – LINQ Integration

LINQ provides SQL-like queries inside C# using IEnumerable or IQueryable.

🔹 LINQ to SQL (ORM)

MyDataContext db = new MyDataContext();
var users = from u in db.Users where u.Age > 18 select u;

🔹 LINQ to Objects

var filtered = list.Where(x => x.IsActive).ToList();

✅ Great for filtering and projecting data in-memory or from databases.

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📌 Summary – Recap & Next Steps

ASP.NET offers powerful, flexible options for data handling—from raw ADO.NET connections to declarative data sources and LINQ integration. Whether you need total control or rapid development, you’ll find the right tools built into the framework.

🔍 Key Takeaways:

• ADO.NET provides fine-grained control over database interaction
• Use SqlDataSource for rapid, no-code data binding
• Use DataBind() to connect UI controls to data sources
• LINQ simplifies querying with readable syntax
• Always use parameters to prevent SQL injection

⚙️ Real-World Applications:

• Admin dashboards with GridView CRUD
• Data-driven reports using LINQ filters
• Web Forms with multi-step form data binding
• Personalization based on user profile data

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❓ Frequently Asked Questions

❓ What is the difference between ADO.NET and SqlDataSource?
✅ ADO.NET is code-driven. SqlDataSource is declarative and quick but less flexible.

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❓ Can I use LINQ with SQL Server in ASP.NET?
✅ Yes. Use LINQ to SQL or Entity Framework for database interaction.

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❓ What is the benefit of DataBind()?
✅ It binds the data to UI controls like GridView, DropDownList, etc., and renders them dynamically.

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❓ How do I prevent SQL injection in ADO.NET?
✅ Use parameterized queries:

cmd.Parameters.AddWithValue("@id", id);

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❓ Which control is best for editable tabular data?
✅ GridView with EditItemTemplate allows inline editing, deleting, and updating rows.

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