Please what's causing and solving of this error message

Question

Please what's causing and solving of this error message in C# (Index was out of range Must be non-negative and less thanthe size of the collection

 

Parameter name:index)?

 

I have a procedure in C# that fill data table in datagridview control… I update a record in d data and after that calling a procedure (ldata() ), when the compiler arrive to dt.clear() the error message above is appeared.

 

as below :

 

.

.

……….(insertbrn_click event)

cmd = new SqlCommand("insert into finance_dep.acount_type (id_cnt, name_cnt, notes_col) values ('" + txt1.Text + "' , '" + txt2.Text + "' , '" + txt3.Text + "') ", cn);

cn.Open();

cmd.ExecuteNonQuery();

cn.Close();

ldata();

……

…

 

When I insert new record is work correctly… but when perform update as below and call a procedure (ldata() )

 

When the compiler arrive to command: dt.clear() an error message was appeared. Since after error message appear the table is updated … why this error appear and solve it?

 

(update_click event)

cmd = new SqlCommand("select * from finance_dep.acount_type", cn);

cn.Open();

dr = cmd.ExecuteReader();

dt.Clear(); // error here

dt.Load(dr);

dgv1.DataSource = dt;

dgv1.Columns[0].HeaderText = "??? ??????";

dgv1.Columns[1].HeaderText = "??? ??????";

dgv1.Columns[2].HeaderText = "?????????";

cn.Close();

void ldata()

{

try

{

//int i = 0;

cmd = new SqlCommand("select * from finance_dep.acount_type", cn);

cn.Open();

dr = cmd.ExecuteReader();

dt.Clear(); // error here

dt.Load(dr);

dgv1.DataSource = dt;

dgv1.Columns[0].HeaderText = "??? ??????";

dgv1.Columns[1].HeaderText = "??? ??????";

dgv1.Columns[2].HeaderText = "?????????";

cn.Close();