ADO.NET Datasets - MSDN Documentation

Datasets

A Dataset object represents a collection of DataTable objects. Together, these objects mimic the structure of a database, providing a disconnected, in-memory representation of data. Datasets are central to ADO.NET's data access capabilities, enabling efficient handling of data manipulation and synchronization between client and server.

Key Features of Datasets

Disconnected Architecture: Datasets can be populated with data and then worked with independently of the data source. This is crucial for applications that need to function without a constant database connection, such as mobile or web applications.
In-Memory Data Representation: A Dataset contains one or more DataTable objects, each representing a table of data. These tables can be related to each other using DataRelation objects, forming a relational structure in memory.
Schema and Data: A Dataset can hold both the schema (structure) and the data itself. This makes it versatile for scenarios where you need to transfer complex data structures.
XML Support: Datasets have robust support for reading and writing their contents (both schema and data) to and from XML. This is invaluable for data exchange and persistence.
Change Tracking: Datasets track changes made to the data within their tables. This allows for efficient updates by sending only the modified rows back to the data source.

Working with Datasets

The process of using a Dataset typically involves the following steps:

Creating a Dataset: Instantiate a new Dataset object.
Populating the Dataset: Use a DataAdapter (e.g., SqlDataAdapter, OleDbDataAdapter) to fill the Dataset with data from a data source. This is usually done by executing a command and mapping the results to a DataTable within the Dataset.
Accessing Data: Navigate through the DataTable objects in the Dataset to access rows and columns.
Manipulating Data: Modify, add, or delete rows within the DataTable objects.
Updating the Data Source: Use the DataAdapter to send any changes made in the Dataset back to the original data source.

Example: Creating and Populating a Dataset

                
using System.Data;
using System.Data.SqlClient;

// Assume connectionString and sqlQuery are defined

// Create a SqlConnection
using (SqlConnection connection = new SqlConnection(connectionString))
{
    // Create a SqlDataAdapter
    using (SqlDataAdapter adapter = new SqlDataAdapter(sqlQuery, connection))
    {
        // Create a Dataset object
        DataSet dataSet = new DataSet();

        // Fill the Dataset with data
        // The data will be placed into a DataTable with a default name like "Table1"
        adapter.Fill(dataSet);

        // You can specify a table name if you prefer
        // adapter.Fill(dataSet, "Customers");

        // Now you can access the data
        if (dataSet.Tables.Count > 0)
        {
            DataTable customersTable = dataSet.Tables[0]; // Or dataSet.Tables["Customers"]
            foreach (DataRow row in customersTable.Rows)
            {
                Console.WriteLine($"Customer Name: {row["CustomerName"]}");
            }
        }
    }
}
                
            

Note: While DataSet is powerful for disconnected scenarios and complex data manipulation, for simpler, forward-only data reading scenarios, consider using DataReader for better performance.

.NET Documentation

Datasets

Key Features of Datasets

Working with Datasets

Example: Creating and Populating a Dataset

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