how to write update query

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ASP.NET

SQL-Server-2008R2

i have an attendance database of college students.
my attendance database contain columns as follows:
date|1|2|3|4|5|6|7|8|9|10|
where 1,2,3,4...10 are the roll numbers.
i am using gridview to display roll_no,name and checkbox column to mark present and absent.
i want to write update query.my current code not executing but values in database are not updating.
my code:
//initializing with todays date and default values for each roll_no as 1
string query = "insert into MCOM values(getdate(),1,1,1,1,1,1,1,1,1,1)";
SqlCommand cmd2 = new SqlCommand(query, con);
cmd2.ExecuteNonQuery();

foreach (GridViewRow gvrow in gvEmp.Rows)
{
CheckBox chk = (CheckBox)gvrow.FindControl("chkSelect");
if (chk != null & chk.Checked)
{

int c = gvrow.RowIndex + 1;
TextBox1.Text = "["+c+"]";
// as textbox contain roll_no(eg.1,2,3....10) for each iteration
string query = "update MCOM set " + TextBox1.Text + "=1 where date=getdate()";
SqlCommand cmd2 = new SqlCommand(query, con);
cmd2.ExecuteNonQuery();
}
else
{
int c = gvrow.RowIndex + 1;
TextBox1.Text = "[" + c + "]";
string query = "update MCOM set " + TextBox1.Text + "=0 where date=getdate()";

SqlCommand cmd1 = new SqlCommand(query, con);
cmd1.ExecuteNonQuery();

}
}

please tell me why my code is executing without errors but still no change in database table.