DataRow

In C# a DataTable has columns, and it has rows. Each cell in a row contains a unit of information. Its type is determined by its column.

Class details

In System.Data, we access the DataRow class. Often we use this class when looping over or accessing a DataTable. These classes drive data programs.

Add

With a DataTable, we usually need to add DataRows. This example method shows how to first add DataColumns. It adds 2 DataRows with the fields indicated in those columns.

using System;
using System.Data;

class Program
{
    static void Main()
    {
        var table = GetTable();
        Console.WriteLine("DONE");
    }

    static DataTable GetTable()
    {
        DataTable table = new DataTable();
        table.Columns.Add("Weight", typeof(int));
        table.Columns.Add("PetType", typeof(string));

        // Add rows.
        table.Rows.Add(10, "dog");
        table.Rows.Add(20, "cat");
        return table;
    }
}
DONE

Object array

We create an object array to add to the DataRowCollection on DataTable. This helps when we need to construct the values in code, or pass the arrays around in methods.

using System;
using System.Data;

class Program
{
    static void Main()
    {
        DataTable table = GetTable();
        //
        // We can instantiate a new object array and add it as a row.
        //
        object[] array = new object[4];
        array[0] = 7;
        array[1] = "Candy";
        array[2] = "Yorkshire Terrier";
        array[3] = DateTime.Now;
        table.Rows.Add(array);
    }

    static DataTable GetTable()
    {
        // Here we create a DataTable with four columns.
        DataTable table = new DataTable();
        table.Columns.Add("Weight", typeof(int));
        table.Columns.Add("Name", typeof(string));
        table.Columns.Add("Breed", typeof(string));
        table.Columns.Add("Date", typeof(DateTime));

        // Here we add five DataRows.
        table.Rows.Add(57, "Koko", "Shar Pei", DateTime.Now);
        table.Rows.Add(130, "Fido", "Bullmastiff", DateTime.Now);
        table.Rows.Add(92, "Alex", "Anatolian Shepherd Dog", DateTime.Now);
        table.Rows.Add(25, "Charles", "Cavalier King Charles Spaniel", DateTime.Now);
        table.Rows.Add(7, "Candy", "Yorkshire Terrier", DateTime.Now);
        return table;
    }
}

Get DataRow

Sometimes we need to obtain a reference to a DataRow. This reference can be used for calling Delete() or other methods, or for passing it as a parameter to methods.

using System;
using System.Data;

class Program
{
    static void Main()
    {
        //
        // Get the first row from the DataTable.
        //
        DataTable table = GetTable();
        DataRow row = table.Rows[0];
        Console.WriteLine(row["Breed"]);
        //
        // Get the last row in the DataTable.
        //
        DataRow last = table.Rows[table.Rows.Count - 1];
        Console.WriteLine(last["Breed"]);
    }
}
Shar Pei
Yorkshire Terrier

Loop

Every DataRow will contain cells or fields. We often need to examine these values. Here we access the ItemArray on a DataRow, and then test each field in that row.

using System;
using System.Data;

class Program
{
    static void Main()
    {
        //
        // Get the first row and loop over its ItemArray.
        //
        DataTable table = GetTable();
        DataRow row = table.Rows[0];
        foreach (object item in row.ItemArray)
        {
            if (item is int)
            {
                Console.WriteLine("Int: {0}", item);
            }
            else if (item is string)
            {
                Console.WriteLine("String: {0}", item);
            }
            else if (item is DateTime)
            {
                Console.WriteLine("DateTime: {0}", item);
            }
        }
    }
}
Int: 57
String: Koko
String: Shar Pei
DateTime: 4/6/2009 4:10:31 PM

Remove

There are Remove and RemoveAt methods on the DataRow collection. These work differently, but in both cases you must be certain (after removal) that you are accessing valid data.

using System;
using System.Data;

class Program
{
    static void Main()
    {
        //
        // Get the first row for the DataTable
        //
        DataTable table = GetTable();
        //
        // Get the row and remove it.
        //
        DataRow row = table.Rows[0];
        table.Rows.Remove(row);
        //
        // You can no longer access row[0].
        //
    }
}
System.Data.RowNotInTableException:
This row has been removed from a table and does not have any data.
BeginEdit() will allow creation of new data in this row.

Delete

This will cleanly delete a DataRow. When you try to access that row's index, you will get the next row. The DataRow erases the row. You cannot access it all after you call Delete.

using System;
using System.Data;

class Program
{
    static void Main()
    {
        //
        // Get the first row for the DataTable
        //
        DataTable table = GetTable();
        DataRow row = table.Rows[0];
        //
        // Delete the first row.
        // ... This means the second row is the first row.
        //
        row.Delete();
        //
        // Display the new first row.
        //
        row = table.Rows[0];
        Console.WriteLine(row["Name"]);
    }
}
Fido

Field

There is a Field generic method on DataRow that returns strongly-typed fields without any casting. This provides clearer code and exploits the power of generic collections.

Summary

DataRow is a powerful collection in System.Data. It can help your data-driven program and keep its code understandable.

Linked to DataTable

The DataRow is used in almost every program that also uses the DataTable type. For many programs, a List or Dictionary is a better choice.