DataRow: Select cell value by a given column name

I have a problem with a DataRow that I'm really struggling with.

The datarow is read in from an Excel spreadsheet using an OleDbConnection.

If I try to select data from the DataRow using the column name, it returns DBNull even though there is data there.

But it's not quite that simple.

datarow.Table.Columns[5].ColumnName returns "my column".

datarow["my column"] returns DBNull.

datarow[5] returns 500.

datarow[datarow.Table.Columns[5].ColumnName] returns DBNull.开发者_开发问答 (just to make sure its not a typo!)

I could just select things from the datarow using the column number, but I dislike doing that since if the column ordering changes, the software will break.

Which version of .NET are you using? Since .NET 3.5, there's an assembly System.Data.DataSetExtensions, which contains various useful extensions for dataTables, dataRows and the like.

You can try using

row.Field<type>("fieldName");

if that doesn't work, you can do this:

DataTable table = new DataTable();
var myColumn = table.Columns.Cast<DataColumn>().SingleOrDefault(col => col.ColumnName == "myColumnName");
if (myColumn != null)
{
    // just some roww
    var tableRow = table.AsEnumerable().First();
    var myData = tableRow.Field<string>(myColumn);
    // or if above does not work
    myData = tableRow.Field<string>(table.Columns.IndexOf(myColumn));
}

This must be a new feature or something, otherwise I'm not sure why it hasn't been mentioned.

You can access the value in a column in a DataRow object using row["ColumnName"]:

DataRow row = table.Rows[0];
string rowValue = row["ColumnName"].ToString();

I find it easier to access it by doing the following:

        for (int i = 0; i < Table.Rows.Count-1; i++) //Looping through rows
        {
            var myValue = Table.Rows[i]["MyFieldName"]; //Getting my field value

        }

Hint

DataTable table = new DataTable();
table.Columns.Add("Column#1", typeof(int));
table.Columns.Add("Column#2", typeof(string));
table.Rows.Add(5, "Cell1-1");
table.Rows.Add(130, "Cell2-2");

EDIT: Added more

string cellValue = table.Rows[0].GetCellValueByName<string>("Column#2");

public static class DataRowExtensions
{
    public static T GetCellValueByName<T>(this DataRow row, string columnName)
    {
        int index = row.Table.Columns.IndexOf(columnName);
        return (index < 0 || index > row.ItemArray.Count()) 
                  ? default(T) 
                  : (T) row[index];        
    }
}

On top of what Jimmy said, you can also make the select generic by using Convert.ChangeType along with the necessary null checks:

public T GetColumnValue<T>(DataRow row, string columnName)
  {
        T value = default(T);
        if (row.Table.Columns.Contains(columnName) && row[columnName] != null && !String.IsNullOrWhiteSpace(row[columnName].ToString()))
        {
            value = (T)Convert.ChangeType(row[columnName].ToString(), typeof(T));
        }

        return value;
  }

You can get the column value in VB.net

Dim row As DataRow = fooTable.Rows(0)
Dim temp = Convert.ToString(row("ColumnName"))

And in C# you can use Jimmy's Answer, just be careful while converting it to ToString(). It can throw null exception if the data is null instead Use Convert.ToString(your_expression) to avoid null exception reference

for (int i=0;i < Table.Rows.Count;i++)
{
      Var YourValue = Table.Rows[i]["ColumnName"];
}

Be careful on datatype. If not match it will throw an error.

var fieldName = dataRow.Field<DataType>("fieldName");

Simple solution: Assume sqlDt contains the DataTable, then this will give you the content of the column named "aaa" in row is:

Dim fldContent = sqlDte.Rows(iz).ItemArray(sqlDte.Columns.Item("aaa").Ordinal)
Console.WriteLine("aaa = " & fldContent)   

Edited code formatting