Datatable cell vale change not working

Question

Hi ,

I want to change the date format for all the rows for a speciific column in a datatable but when i am assigning the changed value to it its not reflecting.

foreach (DataRow dr in dBTable.Rows)
{
dr[4] = Convert.ToDateTime(dr[4]).ToString("dd-MMM-yy");
}

Can anyone please help?

Thanks

Answer 1

Hello,

A DataTable is for storing data, not for changing the format in the case of a DateTime, no different from storing a DateTime in a database table.

If displaying in say a DataGridView, set the format.

Code

public Form1()  
{  
    InitializeComponent();  
      
    Shown += OnShown;  
    dataGridView1.AutoGenerateColumns = false;  
}  
  
private void OnShown(object sender, EventArgs e)  
{  
    var table = new DataTable();  
  
    table.Columns.Add(new DataColumn("SomeDate", typeof(DateTime)));  
  
    table.Rows.Add(new DateTime(2021,1,1));  
    table.Rows.Add(new DateTime(2021,2,1));  
    table.Rows.Add(new DateTime(2021,3,1));  
  
    dataGridView1.DataSource = table;  
}  

Then we can do the following

private void button1_Click(object sender, EventArgs e)  
{  
    var table = (DataTable) dataGridView1.DataSource;  
  
    StringBuilder sb = new StringBuilder();  
    foreach (DataRow row in table.Rows)  
    {  
        sb.AppendLine(row.Field<DateTime>("SomeDate")  
            .ToString("dd-MMM-yy"));  
    }  
  
    MessageBox.Show(sb.ToString());  
}  

Or

var datesFormatted = ((DataTable) dataGridView1.DataSource)  
    .AsEnumerable()  
    .Select(row => row.Field<DateTime>("SomeDate").ToString("dd-MMM-yy"))  
    .ToArray();  
  
MessageBox.Show(string.Join("\n",datesFormatted));