This is one of those famous .NET interview question which keeps coming up now and then. To answer precisely and shortly convert.tostring
handles nulls while simple tostring() function does not handle null. Below video demonstrates the same practically.
Connection: - This object creates a connection to the database. If you want to do any operation on the database you have to first create a connection object.
Command: - This object helps us to execute SQL queries against database. Using command object we can execute select, insert, update and delete SQL command.
Data reader: - This provides a recordset which can be browsed only in forward direction. It can only be read but not updated. Data reader is good for large number of records where you want to
just browse quickly and display it.
Dataset object: - This provides a recordset which can be read back and in forward direction. The recordset can also be updated. Dataset is like a in memory database with tables, rows and
Data Adapter: - This object acts as a bridge between database and dataset; it helps to load the dataset object.
Common mistakes :- Many developers make a common mistake of answering this question by saying that we have used C# , SQL
server , ASP.NET etc. But please do note that the question is, what is the architecture of your project and not technology.
So a typical answer will be something as below. Please note your answer will vary as per your architecture and
"My current architecture is a simple 3 tier architecture with UI in ASP.NET , middle layer are simple .NET classes and DAL is using
enterprise application blocks.
The UI is responsible to take user inputs , all my business validations are centrally located in middle layer and the data access layer is responsible to execute stored
procedured and SQL queries to SQL Server.
Strongly typed business objects are used to pass data from one layer to other layer. The database of the project is in a 3rd normal form."
So first start with the overall architecture , talk about each layer , how data is passed between each layer and the database design structure.
One very important tip if you can draw a diagram and explain....I think you have the job.