如何使用vb.net在gridview中编写更新代码我得到了错误

我在下面插入了错误行代码：



Sql =更新详情设置Deptartment ='& txtDept.Text& '，tenthMark ='& txtten.Text& '，zthMark ='& txttwel.Text& '，Maths ='& txtmaths.Text& '，Physics ='& txtphy.Text& '，Chemistry ='& txtche.Text& '姓名='& txtName.Text& '







但是我得到了错误：



异常详细信息： System.NullReferenceException：对象引用未设置为对象的实例。





请给我任何帮助







谢谢，

I inserted the error line code in below:

Sql = "Update details set Deptartment= '" & txtDept.Text & "', tenthMark= '" & txtten.Text & "', zthMark= '" & txttwel.Text & "', Maths= '" & txtmaths.Text & "', Physics= '" & txtphy.Text & "', Chemistry= '" & txtche.Text & "' where Name= '" & txtName.Text & "'"



But I got Error this:

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.


Please any one help to me



Thank You,