C# DataRow Examples

Use the DataRow type from the System.Data namespace. Get, add and remove rows.

DataRow. A table has columns. It has rows. Each cell in a row contains a unit of information. Its type is determined by its column.DataTable

In System.Data, we access a DataRow. 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 5 DataRows with the fields indicated in those columns.

DataColumn: This is a separate class. One is added when we invoke Columns.Add on a DataTable. This is confusing at first.

DataColumn

GetTable: The DataTable is populated with five rows, each a separate dog with four data cells.

Add: Rows (a DataRowCollection) has an Add method that receives an object array. The array must have the expected number of elements.

C# program that uses DataRow 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; }

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.

Note: The object array here has an array Length equal to the number of columns. Object arrays can store any element type.

Array Length Object Array

C# program that uses object array with DataTable 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); } }

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.

Here: We use the Rows indexer, Rows[0], to get the first row. We get the last row in the Rows collection by subtracting 1 from the Count.

C# program that gets DataRows 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"]); } } Output 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.DataTable, foreach

Note: You can avoid casting with the Field generic method. Please see the section further down for more info.

Here: We loop over the ItemArray with the foreach-loop and then test each field. This helps with flawed or invalid data.

C# program that uses foreach on DataRow 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); } } } } Output 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.

Next: We remove the first row using Remove. If we try to access the DataRow, the runtime will throw an exception.

Important: Please remember that the exceptions are there to help you debug your program quicker.

C# program that removes DataRow 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]. // } } Output 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.

C# program that deletes DataRow 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"]); } } Output 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.Field

So: You can, for example, access int, string, and DateTime fields using the Field method.

Int, uint Strings DateTime

Type: The type parameter, in sharp brackets, accepts the field type, while the function parameter accepts the field index.

A 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.

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C# DataRow Examples

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