Using LINQ to Query DataTables

How to Perform LINQ Queries on a DataTable in C#?

For this example, let’s create a DataTable and populate it with some sample data.

var dt = new DataTable("Person");
dt.Columns.Add("ID", typeof(int));
dt.Columns.Add("Name", typeof(string));
dt.Columns.Add("Age", typeof(int));

// Add some rows to the DataTable
dt.Rows.Add(1, "Alice", 30);
dt.Rows.Add(2, "Bob", 25);
dt.Rows.Add(3, "Charlie", 35);
dt.Rows.Add(4, "David", 28);

Now, you can use LINQ queries to query the DataTable.

For example, if you want to retrieve all the rows where the age is greater than 30:

var rows = from o in dt.AsEnumerable()
           where o.Field<int?>("Age") > 30
           orderby o.Field<int?>("Age") descending
           select o;

foreach (var row in rows)
    Console.WriteLine($"ID: {row.Field<int>("ID")}, Name: {row.Field<string>("Name")}, Age: {row.Field<int?>("Age")}");

Output:

ID: 3, Name: Charlie, Age: 35

You can also use method syntax to achieve the same results. For example, retrieving names where the age is under 30:

var rows = dt.AsEnumerable()
                .Where(row => row.Field<int?>("Age") < 30)
                .Select(row => new { ID = row.Field<int>("ID"), Name = row.Field<string>("Name"), Age = row.Field<int>("Age") });

The DataTable class doesn’t directly support LINQ queries, which is why we need to use the AsEnumerable() method to enable LINQ querying.