ADO.NET, as a Microsoft’s framework, has the potential to create a dominant market position. You can broaden your horizons by gaining hands-on experience with the ADO.NET framework. Here,we have covered most of the regularly asked ADO.NET Interview Questions on various companies.
'ADO.NET is a component of the.NET framework that employs communication across relational and non-relational systems. It has a detached architecture, which enables programmers to access data and data services from a database without relying on the data source. A thorough understanding of this technology will be incredibly advantageous in terms of development.
This ADO.NET Interview Questions with Answers blog contains questions that have been thoroughly researched and curated by ADO.NET industry experts.
Frequency Asked interview questions
Active Data Object is abbreviated as ADO, and ADO.NET is a set of .NET libraries for ADO. ADO.NET is a managed library used by .NET programmes to communicate with data sources via a driver or provider.
Microsoft introduced ADO.NET, a new version of Active X Data Objects (ADO) in the .NET framework. Using the ADO.NET library's comprehensive set of classes, any .NET application, whether Windows or web-based, can communicate with the database. Using either a connected or disconnected design, data can be accessed from any database.
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ADO.NET components are divided into three categories:
The disconnected components form the foundation of the ADO.NET framework. These components (or classes) can be used with or without data providers. A DataTable object, for example, can be used with or without providers, and shared or common components are the basic classes for data providers.
The foundation classes for data providers that are shared by all data providers are known as shared or common components.The data provider components are purpose-built to operate with many types of data sources. Odbc data providers, for example, work with ODBC data sources, while OleDb data providers work with OLE-DB data sources.
The ADO.NET components model is depicted in the graphic below, which demonstrates how the components work.
The table below demonstrates the difference between ADO and ADO.NET:
ADO | ADO.NET |
It is based on Component Object Modelling (COM). | It is based on the Common Language Runtime (CLR). |
To access the data store, it functions in connected mode. | It does not work in disconnected mode and requires an active connection to access the data store. |
It accesses and stores data from the data sources using the RecordSet object. | It accesses and stores data from the data sources using a DataSet object. |
It includes a locking feature. | It does not have a locking feature. |
Binary data is used to store information. | The data is saved in XML format. |
XML integration is not supported. | It allows for XML integration. |
It is impossible to send numerous transactions using a single connection instance. | You can transmit many transactions from a single connection instance. |
Only client-side cursors are available for creation. | Cursors can be built on both the client and server sides. |
In a RecordSet, it provides sequential row access. | DataSet makes use of a collection-based hierarchy to provide non-sequential data access. |
It will combine data from several tables using SQL JOINS and UNIONS. Fetching records from many tables at the same time is not possible. | It will employ DataRelational objects instead of JOINS and UNIONS to integrate data from various tables. As a result, various tables' records are kept separately. |
A DataSet object belongs to the succession of disconnected components. Tables, rows, columns, and relationships are all part of the DataSet. A DataSet is made up of DataTables, and each DataTable is made up of DataRows, DataRelations, and DataColumns. A DataTable corresponds to a database table. Because you filled the preceding DataSet using a SELECT query on the Order table, it includes a DataTable that corresponds to the Orders table.
The ability to reuse your database connection is known as connection pooling. This means that enabling Connection pooling in the connection object allows the connection to be shared among multiple users.
Connection pooling is a mechanism used by ADO.NET to reduce the cost of initiating and closing connections many times. When a request to the database is performed, connection pooling reuses active connections with the same connection string rather than generating new ones. It entails the usage of a connection manager, which is in charge of keeping track of a pool of accessible connections for a given connection string. If multiple connection strings request connection pooling, several pools exist.
The following are the prerequisites for connection pooling:
A Data Adapter is a collection of data instructions and a database connection that may be used to populate a dataset and update a SQL Server database. To complete the dataset and update a SQL Server database, a Data Adapter has a set of data instructions and a database connection. Data Adapters connect a data source to a dataset. Data Adapters are created based on the data source. The Data Adapter classes and their data sources are shown in the table below.
Provider-Specific Data Adapter classes | Data Source |
SqlDataAdapter | SQL Server |
OledbDataAdapter | OLE DB provider |
OdbcDataAdapter | ODBC driver |
OracleDataAdapter | Oracle |
The two major ways that a Data Adapter supports are
Closing an application in the ADO.net framework is important because they impair the applications' scalability and dependability.
Because open connections are always vulnerable to attacks, 'open connections as late as feasible and close them as early as possible is a good rule of thumb. We can use the 'final' block or the USING statement to 'close' the connections.
A DataAdapter and a DataSource are connected by a Connection object (via Command). When creating a connection, you must provide a data provider and a data source. Depending on the type of data source, these two also allow you to select the user ID and password. A connection, a data source, and a data adapter's relationship are shown below image.
A DataView allows you to generate many data visualizations in a DataTable, which is useful in data-binding applications. You can present data in the table with completely different type patterns using a DataView, and you may process the data using a filter expression or by row state. A DataView is a dynamic data display whose content, ordering, and membership change in response to changes in the underlying DataTable.
This differs from the DataTable's Select method, which provides a DataRow array from a table based on a filter and/or sort order, with content that reflects changes to the underlying table but membership and ordering that remains constant. The DataView's dynamic capabilities make it useful.
DataSet | DataReader |
DataSet gives us read/write access to data, allowing us to make changes to it. | We can't update the data because DataReader simply allows us to read it. |
It has a disconnected design, which implies that the database data can be accessible even after the database connection has been closed. | It has a linked architecture, which implies that the connection must be opened in order to access the data retrieved from the database. |
It supports a wide range of database tables from various databases. | Only a single table from a single database is supported. |
Because of the overhead, data access is slower. | It allows for faster data access. |
Data scanning can be done both forward and backward. | Data can only be scanned in one direction. |
SqlCommandObject in ADO.NET supports the following execute() methods:
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Transactions are used in ADO.NET when you want to link multiple tasks together and conduct them as a single entity. By ensuring that either all database operations succeed or all database activities fail, the transaction provides data consistency. Consider an application that performs two tasks. It starts by updating the item order database with order information. Second, it deducts a number of requested products from an item inventory table that keeps track of inventory. If one of the jobs fails, both updates must be undone.
In ADO.NET, data binding refers to the process of configuring user interface (UI) controls in a client application to update or retrieve data from data sources such as a database or an XML document. The user is allowed to attach values to a specific control via data binding.
Based on the type of binding supplied, there are two types of data binding:
OLEDB | ODBC |
An API (Application Programming Interface) enables standard data access from many sources. | It's a database management system interface (DataBase Management System). |
Both relational and non-relational databases can be used with it. | It only works with databases that are relational. |
It follows a set of steps. | It's built on the concept of components. |
It's a lot more straightforward to use. | It's a challenge to put into action. |
It improves the loading and extraction of data performance. | In terms of data loading and extraction, it performs worse than OLE DB. |
To connect to an OLE DB data source, use OleDbConnection = New OleDbConnection(connectionString). | To connect to an ODBC data source, use the resource ODBC connect(string data source, string username, string password, [int cursor type]). If this method succeeds, it will return a connection resource handle that may be used to access the database with the following instructions. |
ADO.NET supports the following two types of transactions
The following are some of the properties supplied by the DataReader:
You can utilize a variety of methods with the DataReader:
Data providers are responsible for transmitting data from the client application to the data store. It contains database-specific information. Data providers are useful for connecting to databases, retrieving data, putting it in a dataset, reading it, and updating the database.
The ADO.NET Framework has the following data providers:
The following are some of the reasons why you should use Stored Procedures in ADO.NET:
using System;
using System.Data.SqlClient;
using System.Data;
namespace DataAdapterExample
{
public partial class DataAdapterDemo : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
using (SqlConnection conn = new SqlConnection("data source=.; database=items; integrated security=SSPI"))
{
SqlDataAdapter da = new SqlDataAdapter("Select * from items", conn);
DataSet s = new DataSet();
da.Fill(s);
GridView1.DataSource = s;
GridView1.DataBind();
}
}
}
}
ADO.NET | ASP.NET |
ADO.NET is a.NET foundation library. | ASP.NET is a framework for developing web applications. |
It's a database-accessing technology. | It's a tool for creating dynamic web pages. |
Data can be converted to XML format here. | Here, we can write code in VB.Net, C#, ASP.Net, and other languages. |
It's used to create high-performance client-server database applications that are both dependable and scalable. | Dynamic web pages, online applications, websites, and web services are all made with it. |
A DataSet is a set of database tables that carry data in a row and column format. In ADO.NET, DataSets come in two types. It's as follows:
An example of how to use DataSet is as follows:
using System;
using System.Data.SqlClient;
using System.Data;
namespace DataSetDemo
{
public partial class DataSetExample : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
using (SqlConnection conn = new SqlConnection("data source=.; database=employee; integrated security=SSPI"))
{
SqlDataAdapter da = new SqlDataAdapter("Select * from employee", conn);
DataSet d = new DataSet();
da.Fill(d);
GridView1.DataSource = d;
GridView1.DataBind();
}
}
}
}
DataAdapter, which receives data from the employee table, will fill DataSet in this case. The information from the personnel database will be displayed using this DataSet.
DataTable | DataSet |
A DataTable is a single database table stored in memory. | A DataSet is a memory-based grouping of many database tables. |
It has a column and row collection. | There is a database table collection in it. |
It only allows for the retrieval of a single TableRow at a time. | It allows you to fetch several TableRows at once. |
Because it is a single database table, it will have no relationships with other tables. | It represents a collection of DataTable objects, and there may be a relationship between them in order to get a certain result. |
DataSource objects aren't serialized in this case. | DataSource objects are serialized in this way. |
The data integrity objects UniqueConstraint and ForeignKeyConstraint are not available. | Data integrity can be enforced using the UniqueConstraint and ForeignKeyConstraint objects. |
Object pooling is a memory repository for objects that can be reused without having to be created again. This object pooling alleviates the burden of having to create objects as needed. Whenever an object is required, the object pool manager will process the request and serve it appropriately. It is intended to make the best use of limited resources in order to meet the needs of client requests.
ADO.NET is built on an Object Model, which allows data from a database to be accessed through a data provider. It's a data access technique provided by the Microsoft.Net Framework that allows relational and non-relational systems to communicate using a standard set of components.
The following are the elements of the ADO.NET architecture:
Connected architecture | Disconnected architecture |
It's all about making connections. | It isn't focused on making connections. |
A connected architecture is DataReader. | The DataSet architecture is a disjointed one. |
Connected approaches provide high speed and performance. | Disconnected approaches are slow and inefficient. |
DataReader does not provide data persistence. | DataSet allows you to keep track of your data. |
It stores the data from a single table. | It stores information from many tables. |
The data is read-only, therefore we can't change it. | We can update the info here. |
Example:
public void ExecuteScalarExample()
{
SqlConnection con = new SqlConnection();
con.ConnectionString = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
try
{
SqlCommand cd = new SqlCommand();
cd.Connection = con;
cd.CommandText = "SELECT SUM(SALARY) FROM EMPLOYEE";
cd.CommandType = CommandType.Text;
con.Open();
Int32 SalaryTotal = Convert.ToInt32(cd.ExecuteScalar());
MessageBox.Show("Total Salary of the employee is : " + SalaryTotal.ToString());
cd.Dispose();
con.Dispose();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
We're going to make a SqlConnection and SqlCommand object. The object of the SqlCommand class is passed SQL Statement, which returns a single value. When the ExecuteScalar() function is called, it returns a single value: the total salary of all employees. A message box will display this value.
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To track down changes, the DataSet object includes two methods:
If you wish to undo all modifications made since the DataSet object was loaded, use the RejectChanges() function.
Clone() merely copies the DataSet structure. The replicated structure will contain all of the DataSet's constraints, relations, and DataTable schemas. The data in the DataSet is not copied.
The DataSet structure, as well as the data in the DataSet, is copied using the Copy() method. The original data is unaffected.
An Object Model is the foundation of ADO.NET. Data Provider is used to get data from Datasource. Connection, DataAdapter, DataReader, and Command are examples of data providers. It feeds data to the app and updates the database with the app's modifications.
A data set or a DataReader object can be used by an application to access data.
ADO.NET also allows you to export a dataset as an XML file. The data is written in XML format in an XML representation of a dataset.
ADO.NET technology will certainly help you advance your profession because it has a broad array of applications. We hope the above questions may assist you in landing your dream job.
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Madhuri is a Senior Content Creator at MindMajix. She has written about a range of different topics on various technologies, which include, Splunk, Tensorflow, Selenium, and CEH. She spends most of her time researching on technology, and startups. Connect with her via LinkedIn and Twitter .
What is the difference between ADO and ADO.NET?
What is Connection Pooling in ADO.NET?
What is the DataAdapter Object in ADO.NET?
What is the difference between DataSet and DataReader?
Explain the types of transactions available in ADO.NET
What are the data providers in ADO.NET?