Build insert query as below:
string insert = "INSERT INTO MYTABLE (";
string values = string.Empty;
for (int i = 1; i <= count; i++)
{
insert += "column" + i.ToString();
TextBox txtbox = (TextBox)this.Controls.Find("TextBOX" + i.ToString(), true)[0];
values += "'" + txtbox.Text.Trim() + "'";
if (i != count)
{
insert += ",";
values += ",";
}
}
insert += ") VALUES (" + values + ")";