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Data access is a fundamental part of programming, as it allows you to retrieve, update, and manipulate data. In this article, we will discuss data access in Visual Basic .NET (VB.NET), a popular programming language that allows developers to create a wide range of applications.
When working with data, it’s important to choose the right data access technology. The most common data access technologies in VB.NET are ADO.NET and Entity Framework. ADO.NET is a set of classes and methods that provide a direct way to access data. Entity Framework is an object-relational mapping (ORM) framework that allows you to work with data in an object-oriented way.
The first step in accessing data is to create a connection to the data source. A connection string is a set of key-value pairs that contains information about the data source, such as the server name, user name, and password. Once you have a connection string, you can use it to create a connection object.
Once you have a connection, you can use ADO.NET to execute SQL commands, such as SELECT, INSERT, UPDATE, and DELETE. These commands allow you to retrieve, update, and manipulate data. Additionally, you can use the DataSet and DataTable classes to work with data in a disconnected way.
Alternatively, with Entity Framework, you can use Linq (Language Integrated Query) to query data in an object-oriented way. Instead of writing raw SQL, you can use Linq to select, filter, and join data. Additionally, you can use the DbContext class to perform CRUD operations and manage the database connection.
When working with data, it’s important to handle errors that may occur. This can be done using the Try-Catch block statement. This statement allows you to specify what should happen if an error occurs. For example, if a user enters an incorrect password, an error will occur. To handle this error, you can display a message to the user or redirect them to an error page.
In addition to handling errors, it’s also important to consider the security of your data. One way to improve the security of your data is to use parameterized queries. A parameterized query is a query that contains placeholders for values that are supplied at runtime. This technique helps to prevent SQL injection attacks.
In conclusion, data access is a fundamental part of programming as it allows you to retrieve, update, and manipulate data. VB.NET provides a number of classes and methods that make it easy to work with data, such as ADO.NET and Entity Framework. Understanding the basics of data access is important for every programmer, as it allows you to retrieve and update data in an efficient way. As a beginner, it’s important to practice working with data, handling errors, and implementing security measures in order to improve your coding skills.
Cookbook – VisualBasic.NET for Beginners – Chapter 16 : Data Access
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