ADO.NET Interview Questions & Answers: Master Data Access in .NET

Prepare for your ADO.NET interview with this comprehensive guide covering fundamental and advanced concepts. This resource provides detailed answers to frequently asked ADO.NET interview questions, exploring core objects like DataReader and DataSet, their functionalities, and key differences. Learn about ADO.NET's advantages, its key features, and comparisons with ADO. Explore topics like LINQ, connection pooling, using stored procedures, DataViews, and various ADO.NET data providers. We also cover ADO.NET objects and methods, namespaces, layers, and the differences between DataGrid and DataRepeater, DataReader and DataSet. This guide also covers important features of ADO.NET 2.0 and provides insights into efficient data retrieval and manipulation techniques. Become proficient in ADO.NET and confidently answer interview questions on this critical .NET technology.

Most Asked ADO.NET Interview Questions

What is ADO.NET?

ADO.NET (ActiveX Data Objects .NET) is a set of .NET Framework classes used to access and manipulate data from various databases (SQL Server, MySQL, Oracle, etc.).

Essential ADO.NET Objects

The two primary ADO.NET objects are:

  • DataReader
  • DataSet

DataReader Object

The DataReader object provides a forward-only, read-only stream of data from a data source. It's highly efficient for retrieving data sequentially.

Loading Multiple Tables into a DataSet

Yes, a DataSet can hold data from multiple tables, representing a relational view of the database.

Key Features of ADO.NET

  • Database connectivity across different systems.
  • Data manipulation (Insert, Update, Delete, Select).
  • Data combination from multiple sources.
  • Disconnected architecture for improved performance.

Advantages of ADO.NET

  • Improved programmability.
  • Easier maintenance.
  • Better interoperability.
  • Enhanced performance and scalability.

Classic ADO vs. ADO.NET

ADO ADO.NET
Uses Recordsets. Uses DataAdapters and DataSets.
Binary communication. XML-based data transfer.
Primarily connection-oriented. Disconnected architecture.
Metadata determined at runtime. Metadata known at design time.
Client-side cursors only. Supports client-side and server-side cursors.

What is LINQ?

LINQ (Language Integrated Query) is a .NET language feature that allows you to query data using C# or VB.NET syntax. It simplifies database interactions and integrates well with various data sources.

Data Editing in Repeater Control

No, the Repeater control is read-only; data editing is not directly supported.

Fastest ADO.NET Object for Data Retrieval

The SqlDataReader object is known for its speed in retrieving data.

Connection Pooling

Connection pooling reuses database connections, improving performance by avoiding the overhead of repeatedly establishing new connections.

ADO.NET Connection Pooling Parameters

Parameter Default Value
Connection Lifetime 0
Connection Timeout 15
Max Pool Size 100
Min Pool Size 0
Pooling true
Incr Pool Size 5
Decr Pool Size 1

Using Stored Procedures in ADO.NET

Yes, stored procedures are commonly used in ADO.NET for performance improvements, security, and maintainability.

DataView

A DataView provides a customized view of a DataTable, allowing for filtering, sorting, and editing.

ADO.NET Data Providers

  • SqlClient (for SQL Server)
  • OleDb
  • Odbc

DataReader vs. DataAdapter

DataReader DataAdapter
Forward-only, read-only; faster. Slower; supports updates.
Explicit connection management. Automatic connection management.
Connected. Disconnected.

DataSet Object

The DataSet object represents a disconnected collection of data tables, allowing for offline manipulation.

ADO.NET Namespaces

Namespace Description
System.Data Core data classes (tables, columns, etc.).
System.Data.SqlClient Classes for connecting to SQL Server.
System.Data.Odbc Classes for connecting to ODBC data sources.
System.Data.OracleClient Classes for connecting to Oracle databases.

Layers of ADO.NET

  • Presentation Layer
  • Business Logic Layer
  • Data Access Layer

Reasons for Using Stored Procedures in ADO.NET

  • Improved performance.
  • Easier maintenance.
  • Enhanced security.
  • Reduced execution time.
  • Less network traffic.

DataGrid vs. DataRepeater

DataGrid DataRepeater
Built-in paging and sorting. Requires custom coding for paging.
Handles text data only. Supports embedded objects and other controls.

DataReader vs. DataSet

DataReader DataSet
Forward-only, read-only. Allows for navigation and updates.
Connected. Disconnected.
Single table. Multiple tables with relationships.
Less memory usage. More memory usage.
Read-only. Supports insert, update, and delete operations.

Linked Server

A linked server allows SQL Server to query data sources on remote servers.

Default SqlCommand.CommandTimeout

The default timeout for SqlCommand.CommandTimeout is 30 seconds.

ADO.NET Execute Methods

  • ExecuteScalar: Returns a single value.
  • ExecuteNonQuery: Executes a non-query command (INSERT, UPDATE, DELETE).
  • ExecuteReader: Returns a DataReader.
  • ExecuteXmlReader: Returns an XmlReader.

Important Features of ADO.NET 2.0

  • Bulk copy operations.
  • Batch updates.
  • Data paging.
  • Improved connection details.
  • DataSet.RemotingFormat property.
  • DataTable load and save methods for XML.

Additional Interview Resources

This section lists additional interview resources, not related to ADO.NET:

  • .NET Interview Questions
  • C# Interview Questions
  • SQL Server Interview Questions
  • WCF Interview Questions
  • Java Basics Interview Questions
  • Java OOPs Interview Questions
  • Servlet Interview Questions
  • JSP Interview Questions
  • Spring Interview Questions
  • Hibernate Interview Questions
  • PL/SQL Interview Questions
  • SQL Interview Questions
  • Oracle Interview Questions
  • Android Interview Questions