Retrieve data from a specific row entered by inputbox - sql

Question

I have a button and once clicked you are required to enter the customersID and once entered the data from that whole row should then load into the text box's, checkbox etc but when i do it, it prompts me with my own error i created saying Customer not found because it cant locate the ID of some sort? Any help appreciated!
In my opinion - When it loads * (All) from where ID is i am thinking it is only loading in all that data from that specific row at that Customer ID (in which i want) so i could use rows.items etc to load in my required information? Is this correct or? In general i just need help retrieving the data and putting it into my text boxes and such.
Code:
Private Sub Client(ByVal ans As String)
If con.State = ConnectionState.Closed Then con.Open()
cmd = New OleDbCommand
cmd.Connection = con
cmd.CommandText = "Select * FROM tbl WHERE ID = ?"
cmd.Parameters.Add("?", OleDbType.VarChar).Value = ans
If cmd.ExecuteNonQuery() = 0 Then
MsgBox("Does not exist!", MsgBoxStyle.Critical, "Enter new ID!")
Else
MessageBox.Show("Now loaded.", "Search Complete!", MessageBoxButtons.OK, MessageBoxIcon.Information)
If con.State = ConnectionState.Closed Then con.Open()
'create data adapters
sql = "Select * from tbl"
da = New OleDbDataAdapter(sql, con)
da.Fill(ds, "tbl")
RecCnt = ds.Tables("tbl").Rows.Count 'how many records in ds
'assign data to lables
TxtCI.Text = ds.Tables("tbl").Rows(0).Item(0)
con.Close()
End If
cmd.ExecuteNonQuery()
con.Close()
End Sub
Caller (Search button):
Client(custid)

Answer 1

ExecuteNonQuery cannot work correctly with a SELECT statement. The returned value is the number of the rows affected but a SELECT statement doesn't change, insert or delete any row, so it is always zero.
You should use ExecuteReader (and this removes also the need to use an OleDbDataAdapter, a DataTable/Dataset and the long winded statement lines to retrieve values from the DataSet/Tables/Rows/Columns hierarchy
If con.State = ConnectionState.Closed Then con.Open()
cmd = New OleDbCommand
cmd.Connection = con
cmd.CommandText = "Select * FROM tblcustomer WHERE CustomerID = ?"
cmd.Parameters.Add("?", OleDbType.VarChar).Value = ans
Dim reader As OleDbDataReader = cmd.ExecuteReader()
if reader.Read() Then
TxtCI.Text = reader(0).ToString()
TxtName.Text = reader(1).ToString()
... and so on ...
Else
MsgBox("Customer Does not exist!", ....)
Notice that you could substitute the column index (0,1,2 etc...) with the column name ("CI", "Name" etc...). This is somewhat better because it doesn't depend on the order returned by the SELECT * query (Of course, if you change the columns names you have the same problem but, at least, you should know about the change)