Datatable cell vale change not working

Question

Datatable cell vale change not working

Bikramj 21

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

Daniel Zhang-MSFT 9,646

Hi Bikramj-4545,
I made a simple test and your code worked fine.
In order to see the changes of DateTime in Datatable more intuitively, I display Datatable in dataGridView.

DataTable table = new DataTable();  
private void Form1_Load(object sender, EventArgs e)  
{  
    table.Columns.Add("Dosage", typeof(int));  
    table.Columns.Add("Drug", typeof(string));  
    table.Columns.Add("Diagnosis", typeof(string));  
    table.Columns.Add("Date", typeof(DateTime));  
    table.Rows.Add(25, "Drug A", "Disease A", DateTime.Now);  
    table.Rows.Add(50, "Drug Z", "Problem Z", DateTime.Now);  
    table.Rows.Add(10, "Drug Q", "Disorder Q", DateTime.Now);  
    table.Rows.Add(21, "Medicine A", "Diagnosis A", DateTime.Now);  
    dataGridView1.DataSource = table;  
}  
  
private void button1_Click(object sender, EventArgs e)  
{  
    foreach (DataRow dr in table.Rows)  
    {  
                
        dr[3] = Convert.ToDateTime(dr[3]).ToString("dd-MMM-yy");  
        Console.WriteLine(dr[3]);  
    }  
}

The result:

So what is your DataTable? And please provide more code to reproduce the situation.
Best Regards,
Daniel Zhang

$Opendata858c91 1 Reputation point

2021-08-22T21:24:32.61+00:00

DateTime.Now

Accepted answer

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Daniel Zhang-MSFT 9,646 Reputation points

2021-07-12T08:01:21.673+00:00

Hi Bikramj-4545,
I made a simple test and your code worked fine.
In order to see the changes of DateTime in Datatable more intuitively, I display Datatable in dataGridView.

DataTable table = new DataTable(); private void Form1_Load(object sender, EventArgs e) { table.Columns.Add("Dosage", typeof(int)); table.Columns.Add("Drug", typeof(string)); table.Columns.Add("Diagnosis", typeof(string)); table.Columns.Add("Date", typeof(DateTime)); table.Rows.Add(25, "Drug A", "Disease A", DateTime.Now); table.Rows.Add(50, "Drug Z", "Problem Z", DateTime.Now); table.Rows.Add(10, "Drug Q", "Disorder Q", DateTime.Now); table.Rows.Add(21, "Medicine A", "Diagnosis A", DateTime.Now); dataGridView1.DataSource = table; } private void button1_Click(object sender, EventArgs e) { foreach (DataRow dr in table.Rows) { dr[3] = Convert.ToDateTime(dr[3]).ToString("dd-MMM-yy"); Console.WriteLine(dr[3]); } }

The result:

So what is your DataTable? And please provide more code to reproduce the situation.
Best Regards,
Daniel Zhang
$Opendata858c91 1 Reputation point

2021-08-22T21:24:32.61+00:00

DateTime.Now

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));

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Datatable cell vale change not working

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