Access database doesn't update properly

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I have been creating a software in C#. I tried to update some information in my Access database. Here's my database fields.Date ,total_h, W_hours, delay_h. Date is the Primary key. So I want to Update data where Date="datetimePicker.text". here is the Code What I tried.

C#

try
{
    connection.Open();
    OleDbCommand cmd = new OleDbCommand();
    cmd.Connection = connection;               
    string update = "update summery_data set total_h='"+tHour+"', delay_h='"+delay+"' WHERE Date= " + dateTimePicker1.Text + " ";      
                    cmd.CommandText = update;
                    cmd.ExecuteNonQuery();
                    MessageBox.Show(" Updated successfully");
                    connection.Close();
}
catch(Exception ex)
{
    MessageBox.Show(ex.Message);
}

The Program is running properly without any Exception and displaying the "Updated successfully" message also. But when I open and Check the database the data has not been updated. I can't Understand what the problem is...?. please help me someone knows about it.

What I have tried:

The Program is running properly without any Exception and displaying the "Updated successfully" message also. But when I open and Check the database the data has not been updated.

Posted 26-Jun-16 2:15am

Member 12179104

Updated 26-Jun-16 2:41am

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[no name] 26-Jun-16 8:23am

Check the return value of OleDbCommand. It returns the "number of affected rows". Most probably it is Zero because most probably your WHERE clause does not match.

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OriginalGriff · Answer 1 · 2016-06-26T02:41:00

Don't do it like that. Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.
The chances are that this will cure your problem at the same time: it's very likely that the WHERE clause is not matching any records.

C#

string update = "update summery_data set total_h=@TH, delay_h=@DH WHERE Date=@DAT";
cmd.CommandText = update;
cmd.Parameters.AddWithValue("@TH", tHour);
cmd.Parameters.AddWithValue("@DH", delay);
cmd.Parameters.AddWithValue("@DAT",dateTimePicker1.Value);