asked on

databindings

hello experts ,
I want to query database and retrieve value of a field of table , and put it in textbox1,I wrote these :

Dim cn As OleDbConnection = New OleDbConnection("provider=microsoft.jet.oledb.4.0; _
data source=d:\db1.mdb")
cn.Open()
Dim da As OleDbDataAdapter = New OleDbDataAdapter _("select * from table1 where fname='hossein'", cn)
Dim ds As DataSet = New DataSet
TextBox1.DataBindings.Add("text", ds, "table1.lname")
da.Fill(ds)

but when I run this , error appear :

An unhandled exception of type 'System.ArgumentException' occurred in system.windows.forms.dll

Additional information: Cannot create a child list for field table1.

please help me to correct these codes,
is there better way?
thanks

Sancler

Unless you are using more than one DataTable, you don't need a DataSet, you can just work with a DataTable. If you are using a DataAdapter you do not need explicitly to open the Connection: the DataAdapter opens and closes it automatically. But if you are going explicitly to .Open a Connection, you should always .Close it, too. Unless you are using a strongly typed dataset (i.e. one which is defined at design time) you should put your databinding after, not before, you fill your table. Otherwise, as the error message says, the binding will not be able to find the table/field it is referred to: it won't yet exist.

Rolling all that together (and assuming that your table has a field called "lname") try this.

Dim cn As OleDbConnection = New OleDbConnection("provider=microsoft.jet.oledb.4.0; _
data source=d:\db1.mdb")
Dim da As OleDbDataAdapter = New OleDbDataAdapter _("select * from table1 where fname='hossein'", cn)
Dim dt As New DataTable
da.Fill(dt)
TextBox1.DataBindings.Add("text", dt, "lname")

Roger

farhadtolooie

ASKER

hello roger
I wrote your code and run it , but this error occur:

An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in system.data.dll

what doyou think about it?
what's the problem?

farhad

ASKER CERTIFIED SOLUTION

Sancler

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