100 Must-Know ADO.NET Interview Questions and Answers 2025

ADO.NET Fundamentals

1.
What is ADO.NET and what are its main components?
2.
How does ADO.NET differ from classic ADO?
3.
What is the role of the DataSet in ADO.NET?
4.
Explain the differences between DataSet and DataReader.
5.
What are the key classes in ADO.NET?
6.
What is the use of the Connection object in ADO.NET?
7.
How do you handle transactions in ADO.NET?
8.
Describe the Connection Pooling in ADO.NET and how it can be configured.
9.
What is the purpose of Command objects in ADO.NET?
10.
Can you explain what a DataAdapter does in ADO.NET?
11.
What is a DataRelation object in a DataSet?
12.
How do you filter and sort data in a DataSet?

ADO.NET Advanced Features

13.
What is a DataProvider and how do you choose one?
14.
Can you define what a Parameterized Query is in ADO.NET?
15.
Explain how to implement optimistic concurrency in ADO.NET.
16.
Describe how to use the SqlBulkCopy class.
17.
What are Typed and Untyped DataSets?
18.
Explain the process of updating a database with changes from a DataSet.
19.
Describe how to handle NULL database values in ADO.NET.
20.
What is the role of the Entity Framework in ADO.NET?
21.
How do you use Transactions with a DataAdapter?
22.
What is a Connection String and what are the common parameters that it may contain?

ADO.NET Connection and Command

23.
How do you open and close a database connection in ADO.NET?
24.
Explain the ExecuteNonQuery, ExecuteScalar and ExecuteReader methods of the Command object.
25.
What is the purpose of the IDbConnection and IDbCommand interfaces?
26.
Discuss how CommandBehavior affects the behavior of data readers.
27.
What are the differences between ExecuteScalar, ExecuteReader, and ExecuteXmlReader?
28.
How do you create and use a stored procedure with ADO.NET?
29.
What are prepared statements and how do you use them in ADO.NET?

ADO.NET DataAdapter and DataSet

30.
How does a DataAdapter manage the connection to a data source?
31.
Explain the Fill method of DataAdapter and how it populates a DataSet or DataTable.
32.
How do you update the underlying data source with changes in a DataSet?
33.
What is a DataSet schema and how is it created and used?
34.
How can you merge contents of two DataSets?
35.
Discuss ways to improve the performance of DataSet objects.
36.
How do you ensure that your ADO.NET application is scalable?

ADO.NET Transaction and Concurrency

37.
What is an Isolation Level in transactions? List the different types.
38.
Describe the difference between pessimistic and optimistic concurrency control.
39.
How can you implement batch updates in ADO.NET?

ADO.NET with XML

40.
Explain how ADO.NET interacts with XML.
41.
What is an XML Schema Definition (XSD) and how can it be used with ADO.NET?
42.
How do you read and write XML data with ADO.NET?

ADO.NET Exceptions and Error Handling

43.
How do you handle exceptions in ADO.NET?
44.
What are the common exceptions you might encounter when using ADO.NET and how do you handle them?
45.
How do you perform error logging in ADO.NET applications?

ADO.NET Best Practices

46.
What is the recommended way to secure your ADO.NET connection strings?
47.
What are the best practices for using ADO.NET in high-performance applications?
48.
How can you minimize the use of resources when working with ADO.NET?
49.
Can you explain the use of Using statement in connection and command objects?
50.
What are some common performance considerations when using ADO.NET?

ADO.NET Data Types and Constraints

51.
What is the difference between a DataSet and a DataTable?
52.
How do you add a new DataColumn to a DataTable?
53.
Describe the role of the DataView in ADO.NET.
54.
What are the constraints in a DataSet and how do they work?
55.
What data types can be used within a DataTable?

ADO.NET Data Relationships

56.
How do you define a relationship between tables in a DataSet?
57.
What is a ForeignKeyConstraint and how do you use it in ADO.NET?
58.
Describe how to navigate through master-detail records in a DataSet.

ADO.NET and LINQ (Language Integrated Query)

59.
What is LINQ to DataSet and how do you use it?
60.
How do LINQ queries differ when used with DataSet vs. DataReader?
61.
Explain the role of DataContext in LINQ to SQL.
62.
Describe how you would perform a join between two DataTables using LINQ.

ADO.NET Asynchronous Operations

63.
How do you perform asynchronous data operations in ADO.NET?
64.
Explain the impact of async/await keywords on database operations.
65.
What methods support asynchronous execution in SqlCommand?

Interacting with Different Databases

66.
How would you switch between different database systems using ADO.NET?
67.
What changes might be required when moving from a SQL Server database to Oracle using ADO.NET?
68.
Can you explain how to use ADO.NET with a MySQL database?

ADO.NET Entity Framework

69.
How does ADO.NET Entity Framework differ from ADO.NET?
70.
What is the Code First approach in Entity Framework and how does it work with ADO.NET?
71.
Explain the Database First approach in Entity Framework.
72.
What are Entity Framework migrations and how do they integrate with ADO.NET?

Advanced ADO.NET Techniques

73.
How do you handle bulk insert operations with ADO.NET?
74.
Can you explain the use of Table-Valued Parameters in ADO.NET?
75.
Describe the process of implementing a Custom Data Provider for ADO.NET.
76.
How do you implement Full-Text Search queries within ADO.NET?

ADO.NET Performance Tuning

77.
What are some methods to profile and tune the performance of ADO.NET applications?
78.
How would you use caching to enhance the performance of an ADO.NET application?
79.
What are some common anti-patterns that degrade ADO.NET performance?

ADO.NET Security

80.
Discuss the security considerations when using ADO.NET to connect to a database.
81.
How do you use Windows Authentication with ADO.NET?
82.
Explain how to encrypt sensitive ADO.NET configuration information.
83.
What is SQL Injection and how can ADO.NET help prevent it?

ADO.NET Integration and Interoperability

84.
How do you integrate ADO.NET with other .NET Framework components?
85.
Can ADO.NET interact with RESTful services, and if so, how?
86.
How does ADO.NET support interoperability with non-.NET languages?

ADO.NET Deployment and Configuration

87.
What are the considerations for deploying an ADO.NET application?
88.
How do you manage database connections and perform versioning in a deployment scenario?
89.
Describe the process of using ADO.NET in a multi-tier application architecture.

ADO.NET and Transaction Management

90.
What is System.Transactions namespace and how does it relate to ADO.NET?
91.
Explain distributed transaction management with ADO.NET.

ADO.NET Object-Relational Mapping (ORM)

92.
Define Object-Relational Mapping (ORM) as it pertains to ADO.NET.
93.
How does ADO.NET fit into an ORM strategy?

ADO.NET Diagnostic and Troubleshooting

94.
How do you troubleshoot connectivity issues in ADO.NET?
95.
What tools can be used for diagnosing problems in an ADO.NET application?

ADO.NET Extensibility

96.
How can you extend the functionalities of ADO.NET?
97.
What options does ADO.NET provide for custom data serialization?

ADO.NET and .NET Framework Integration

98.
How does ADO.NET interact with other .NET namespaces and functionalities?
99.
How do you handle data concurrency in .NET applications using ADO.NET?

Modern ADO.NET Uses and Practices

100.
Describe how modern .NET development practices (like .NET Core and .NET 5/6+) have affected the use and evolution of ADO.NET.

Ace your next tech interview with confidence

Explore our carefully curated catalog of interview essentials covering full-stack, data structures and algorithms, system design, data science, and machine learning interview questions

100 ADO.NET interview questions

What is ADO.NET and what are its main components?

How does ADO.NET differ from classic ADO?

What is the role of the DataSet in ADO.NET?

Explain the differences between DataSet and DataReader.

What are the key classes in ADO.NET?

What is the use of the Connection object in ADO.NET?

How do you handle transactions in ADO.NET?

Describe the Connection Pooling in ADO.NET and how it can be configured.

What is the purpose of Command objects in ADO.NET?

Can you explain what a DataAdapter does in ADO.NET?

What is a DataRelation object in a DataSet?

How do you filter and sort data in a DataSet?

What is a DataProvider and how do you choose one?

Can you define what a Parameterized Query is in ADO.NET?

Explain how to implement optimistic concurrency in ADO.NET.

Describe how to use the SqlBulkCopy class.

What are Typed and Untyped DataSets?

Explain the process of updating a database with changes from a DataSet.

Describe how to handle NULL database values in ADO.NET.

What is the role of the Entity Framework in ADO.NET?

How do you use Transactions with a DataAdapter?

What is a Connection String and what are the common parameters that it may contain?

How do you open and close a database connection in ADO.NET?

Explain the ExecuteNonQuery, ExecuteScalar and ExecuteReader methods of the Command object.

What is the purpose of the IDbConnection and IDbCommand interfaces?

Discuss how CommandBehavior affects the behavior of data readers.

What are the differences between ExecuteScalar, ExecuteReader, and ExecuteXmlReader?

How do you create and use a stored procedure with ADO.NET?

What are prepared statements and how do you use them in ADO.NET?

How does a DataAdapter manage the connection to a data source?

Explain the Fill method of DataAdapter and how it populates a DataSet or DataTable.

How do you update the underlying data source with changes in a DataSet?

What is a DataSet schema and how is it created and used?

How can you merge contents of two DataSets?

Discuss ways to improve the performance of DataSet objects.

How do you ensure that your ADO.NET application is scalable?

What is an Isolation Level in transactions? List the different types.

Describe the difference between pessimistic and optimistic concurrency control.

How can you implement batch updates in ADO.NET?

Explain how ADO.NET interacts with XML.

What is an XML Schema Definition (XSD) and how can it be used with ADO.NET?

How do you read and write XML data with ADO.NET?

How do you handle exceptions in ADO.NET?

What are the common exceptions you might encounter when using ADO.NET and how do you handle them?

How do you perform error logging in ADO.NET applications?

What is the recommended way to secure your ADO.NET connection strings?

What are the best practices for using ADO.NET in high-performance applications?

How can you minimize the use of resources when working with ADO.NET?

Can you explain the use of Using statement in connection and command objects?

What are some common performance considerations when using ADO.NET?

What is the difference between a DataSet and a DataTable?

How do you add a new DataColumn to a DataTable?

Describe the role of the DataView in ADO.NET.

What are the constraints in a DataSet and how do they work?

What data types can be used within a DataTable?

How do you define a relationship between tables in a DataSet?

What is a ForeignKeyConstraint and how do you use it in ADO.NET?

Describe how to navigate through master-detail records in a DataSet.

What is LINQ to DataSet and how do you use it?

How do LINQ queries differ when used with DataSet vs. DataReader?

Explain the role of DataContext in LINQ to SQL.

Describe how you would perform a join between two DataTables using LINQ.

How do you perform asynchronous data operations in ADO.NET?

Explain the impact of async/await keywords on database operations.

What methods support asynchronous execution in SqlCommand?

How would you switch between different database systems using ADO.NET?

What changes might be required when moving from a SQL Server database to Oracle using ADO.NET?

Can you explain how to use ADO.NET with a MySQL database?

How does ADO.NET Entity Framework differ from ADO.NET?

What is the Code First approach in Entity Framework and how does it work with ADO.NET?

Explain the Database First approach in Entity Framework.

What are Entity Framework migrations and how do they integrate with ADO.NET?

How do you handle bulk insert operations with ADO.NET?

Can you explain the use of Table-Valued Parameters in ADO.NET?

Describe the process of implementing a Custom Data Provider for ADO.NET.

How do you implement Full-Text Search queries within ADO.NET?

What are some methods to profile and tune the performance of ADO.NET applications?