Querying DataSets with LINQ to DataSet

LINQ to DataSet is a powerful tool to query DataSets. It allows us to query in-memory data structures such as DataTables and DataSets using simple and expressive C# or VB.NET syntax. In this tutorial, we'll look at how to query DataSets using LINQ to DataSet.

Syntax

var query = from table in dataSet.Tables["TableName"].AsEnumerable()
            where table.Field<int>("ColumnName") > Value
            select table.Field<string>("AnotherColumnName");

Example

Let's create a simple DataSet and query it using LINQ to DataSet.

// Create a DataTable
DataTable dt = new DataTable("Employees");

// Add columns to the DataTable
dt.Columns.Add("EmployeeID", typeof(int));
dt.Columns.Add("FirstName", typeof(string));
dt.Columns.Add("LastName", typeof(string));
dt.Columns.Add("City", typeof(string));

// Add some data to the DataTable
dt.Rows.Add(1, "John", "Doe", "New York");
dt.Rows.Add(2, "Jane", "Smith", "Los Angeles");
dt.Rows.Add(3, "Bob", "Johnson", "Chicago");

// Create a DataSet and add the DataTable to it
DataSet ds = new DataSet();
ds.Tables.Add(dt);

// Query the DataSet using LINQ to DataSet
var query = from table in ds.Tables["Employees"].AsEnumerable()
            where table.Field<string>("City") == "New York"
            select table.Field<string>("FirstName") + " " + table.Field<string>("LastName");

foreach (var name in query)
{
    Console.WriteLine(name);
}

In the above example, we created a DataTable and added some data to it. Then we created a DataSet and added the DataTable to it. Finally, we queried the DataSet using LINQ to DataSet and printed out the results to the console.

Output

After running the above code, the output will be:

John Doe

Explanation

In the above syntax, we use the from keyword to specify the source of the data. We use the AsEnumerable() method to convert the DataTable to an IEnumerable<T>. We use the where keyword to filter the data based on some condition. Finally, we use the select keyword to project the data into a new shape.

In the example above, we queried the "Employees" table and filtered the data based on the "City" column. We projected the data into a new shape by concatenating the "FirstName" and "LastName" columns.

Use

LINQ to DataSet can be used to query in-memory data structures such as DataTables and DataSets. It's a useful tool for filtering and projecting data in a flexible and expressive manner.

Important Points

• LINQ to DataSet is an extension to LINQ that provides querying capabilities for in-memory data structures such as DataTables and DataSets.
• LINQ to DataSet provides a fluent and expressive syntax to filter and project data.
• LINQ to DataSet is optimized for performance and memory usage, making it suitable for large datasets.

Summary

In this tutorial, we learned how to query DataSets using LINQ to DataSet. We've seen how to use the from, where, and select keywords to filter and project data. We've also learned that LINQ to DataSet is an extension to LINQ that provides querying capabilities for in-memory data structures such as DataTables and DataSets.