I am trying to develop a threaded function to create a dataset from an
Oracle database. When querying an elaborate view, queries take a while. I
would like to place and animated wait dialog up while the query runs. I
don't know much about threading, so bear with me. The following code
contains a class that works fine when threading is not used, but fails to
return a dataset when I execute the threading code. Any help would be
appreciated.
Public Class QueryClass
Public QueryString As String
Public DSet As DataSet
Public TblName As String
Public Sub GetOracleDatase t()
SyncLock GetType(QueryCl ass)
Dim connectionStrin g As String =
"Provider=OraOL EDB.Oracle;Data Source=PRODUCTI ON;User
Id=myuser;Passw ord=abc123;"
Dim dbConnection As New
System.Data.Ole Db.OleDbConnect ion(connectionS tring)
Dim dbCommand As New System.Data.Ole Db.OleDbCommand
Dim dataSet As New System.Data.Dat aSet(TblName)
Dim dataAdapter As New System.Data.Ole Db.OleDbDataAda pter
DSet = New DataSet
Try
dbCommand.Comma ndText = QueryString
dbCommand.Conne ction = dbConnection
dataAdapter.Sel ectCommand = dbCommand
dataAdapter.Fil l(DSet, TblName)
Catch e As Exception
Dim logfile As New
System.IO.Strea mWriter("c:\ora cle.log")
logfile.WriteLi ne(e.Message & Chr(13) & "SQL: " &
QueryString)
logfile.Close()
MsgBox(e.Messag e & Chr(13) & "SQL: " & QueryString)
DSet = Nothing
Exit Sub
End Try
End SyncLock
End Sub
End Class
Sub DoThis()
Dim WaitForm As New dlgWait
WaitForm.Show()
WaitForm.Refres h()
Dim Qry As New QueryClass
Dim t As System.Threadin g.Thread
t = New Threading.Threa d(AddressOf Qry.GetOracleDa taset)
t.Priority = Threading.Threa dPriority.Highe st
Qry.QueryString = TextBox1.Text
Qry.TblName = "tbl"
t.Start()
If IsNothing(Qry.D Set) Then
MsgBox("No Dataset")
Exit Sub
End If
DataGrid1.DataS ource = Qry.DSet.Tables (Qry.TblName)
WaitForm.Close( )
End Sub
4  1605 
What is the nature of the exception?
--
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Solutions http://www.kjmsolutions.com
"Lee Moore" <le******@hotma il.com> wrote in message
news:O3******** ******@TK2MSFTN GP03.phx.gbl... I am trying to develop a threaded function to create a dataset from an
Oracle database. When querying an elaborate view, queries take a while. I
would like to place and animated wait dialog up while the query runs. I
don't know much about threading, so bear with me. The following code
contains a class that works fine when threading is not used, but fails to
return a dataset when I execute the threading code. Any help would be
appreciated.
Public Class QueryClass
Public QueryString As String
Public DSet As DataSet
Public TblName As String
Public Sub GetOracleDatase t()
SyncLock GetType(QueryCl ass)
Dim connectionStrin g As String =
"Provider=OraOL EDB.Oracle;Data Source=PRODUCTI ON;User
Id=myuser;Passw ord=abc123;"
Dim dbConnection As New
System.Data.Ole Db.OleDbConnect ion(connectionS tring)
Dim dbCommand As New System.Data.Ole Db.OleDbCommand
Dim dataSet As New System.Data.Dat aSet(TblName)
Dim dataAdapter As New System.Data.Ole Db.OleDbDataAda pter
DSet = New DataSet
Try
dbCommand.Comma ndText = QueryString
dbCommand.Conne ction = dbConnection
dataAdapter.Sel ectCommand = dbCommand
dataAdapter.Fil l(DSet, TblName)
Catch e As Exception
Dim logfile As New
System.IO.Strea mWriter("c:\ora cle.log")
logfile.WriteLi ne(e.Message & Chr(13) & "SQL: " &
QueryString)
logfile.Close()
MsgBox(e.Messag e & Chr(13) & "SQL: " & QueryString)
DSet = Nothing
Exit Sub
End Try
End SyncLock
End Sub
End Class
Sub DoThis()
Dim WaitForm As New dlgWait
WaitForm.Show()
WaitForm.Refres h()
Dim Qry As New QueryClass
Dim t As System.Threadin g.Thread
t = New Threading.Threa d(AddressOf Qry.GetOracleDa taset)
t.Priority = Threading.Threa dPriority.Highe st
Qry.QueryString = TextBox1.Text
Qry.TblName = "tbl"
t.Start()
If IsNothing(Qry.D Set) Then
MsgBox("No Dataset")
Exit Sub
End If
DataGrid1.DataS ource = Qry.DSet.Tables (Qry.TblName)
WaitForm.Close( )
End Sub
No exception, the process just never starts and the value of the dataset
property of the class is null. Remove the threading, and everything works
fine. I'm lost
"vbnetdev" <vb******@commu nity.nospam> wrote in message
news:uc******** ******@TK2MSFTN GP05.phx.gbl... What is the nature of the exception?
--
Get a powerful web, database, application, and email hosting with KJM
Solutions
http://www.kjmsolutions.com
"Lee Moore" <le******@hotma il.com> wrote in message
news:O3******** ******@TK2MSFTN GP03.phx.gbl...I am trying to develop a threaded function to create a dataset from an
Oracle database. When querying an elaborate view, queries take a while. I
would like to place and animated wait dialog up while the query runs. I
don't know much about threading, so bear with me. The following code
contains a class that works fine when threading is not used, but fails to
return a dataset when I execute the threading code. Any help would be
appreciated .
Public Class QueryClass
Public QueryString As String
Public DSet As DataSet
Public TblName As String
Public Sub GetOracleDatase t()
SyncLock GetType(QueryCl ass)
Dim connectionStrin g As String =
"Provider=OraOL EDB.Oracle;Data Source=PRODUCTI ON;User
Id=myuser;Passw ord=abc123;"
Dim dbConnection As New
System.Data.Ole Db.OleDbConnect ion(connectionS tring)
Dim dbCommand As New System.Data.Ole Db.OleDbCommand
Dim dataSet As New System.Data.Dat aSet(TblName)
Dim dataAdapter As New System.Data.Ole Db.OleDbDataAda pter
DSet = New DataSet
Try
dbCommand.Comma ndText = QueryString
dbCommand.Conne ction = dbConnection
dataAdapter.Sel ectCommand = dbCommand
dataAdapter.Fil l(DSet, TblName)
Catch e As Exception
Dim logfile As New
System.IO.Strea mWriter("c:\ora cle.log")
logfile.WriteLi ne(e.Message & Chr(13) & "SQL: " &
QueryString)
logfile.Close()
MsgBox(e.Messag e & Chr(13) & "SQL: " & QueryString)
DSet = Nothing
Exit Sub
End Try
End SyncLock
End Sub
End Class
Sub DoThis()
Dim WaitForm As New dlgWait
WaitForm.Show()
WaitForm.Refres h()
Dim Qry As New QueryClass
Dim t As System.Threadin g.Thread
t = New Threading.Threa d(AddressOf Qry.GetOracleDa taset)
t.Priority = Threading.Threa dPriority.Highe st
Qry.QueryString = TextBox1.Text
Qry.TblName = "tbl"
t.Start()
If IsNothing(Qry.D Set) Then
MsgBox("No Dataset")
Exit Sub
End If
DataGrid1.DataS ource = Qry.DSet.Tables (Qry.TblName)
WaitForm.Close( )
End Sub
Lee,
I suspect what's happening is the read immediately after calling
Thread.Start is seeing that Qry.DSet is nothing because the thread
hasn't set it yet.
If you're using .NET 2.0 then you might find BackgroundWorke r class
helpful. It simplifies of the task of executing code asynchronously.
Brian
Lee Moore wrote: I am trying to develop a threaded function to create a dataset from an
Oracle database. When querying an elaborate view, queries take a while. I
would like to place and animated wait dialog up while the query runs. I
don't know much about threading, so bear with me. The following code
contains a class that works fine when threading is not used, but fails to
return a dataset when I execute the threading code. Any help would be
appreciated.
Public Class QueryClass
Public QueryString As String
Public DSet As DataSet
Public TblName As String
Public Sub GetOracleDatase t()
SyncLock GetType(QueryCl ass)
Dim connectionStrin g As String =
"Provider=OraOL EDB.Oracle;Data Source=PRODUCTI ON;User
Id=myuser;Passw ord=abc123;"
Dim dbConnection As New
System.Data.Ole Db.OleDbConnect ion(connectionS tring)
Dim dbCommand As New System.Data.Ole Db.OleDbCommand
Dim dataSet As New System.Data.Dat aSet(TblName)
Dim dataAdapter As New System.Data.Ole Db.OleDbDataAda pter
DSet = New DataSet
Try
dbCommand.Comma ndText = QueryString
dbCommand.Conne ction = dbConnection
dataAdapter.Sel ectCommand = dbCommand
dataAdapter.Fil l(DSet, TblName)
Catch e As Exception
Dim logfile As New
System.IO.Strea mWriter("c:\ora cle.log")
logfile.WriteLi ne(e.Message & Chr(13) & "SQL: " &
QueryString)
logfile.Close()
MsgBox(e.Messag e & Chr(13) & "SQL: " & QueryString)
DSet = Nothing
Exit Sub
End Try
End SyncLock
End Sub
End Class
Sub DoThis()
Dim WaitForm As New dlgWait
WaitForm.Show()
WaitForm.Refres h()
Dim Qry As New QueryClass
Dim t As System.Threadin g.Thread
t = New Threading.Threa d(AddressOf Qry.GetOracleDa taset)
t.Priority = Threading.Threa dPriority.Highe st
Qry.QueryString = TextBox1.Text
Qry.TblName = "tbl"
t.Start()
If IsNothing(Qry.D Set) Then
MsgBox("No Dataset")
Exit Sub
End If
DataGrid1.DataS ource = Qry.DSet.Tables (Qry.TblName)
WaitForm.Close( )
End Sub
For a start, take out the MessageBox statements when running on a background
thread. Use tracing or progress events.
"Lee Moore" <le******@hotma il.com> wrote in message
news:On******** ******@TK2MSFTN GP05.phx.gbl... No exception, the process just never starts and the value of the dataset
property of the class is null. Remove the threading, and everything works
fine. I'm lost
"vbnetdev" <vb******@commu nity.nospam> wrote in message
news:uc******** ******@TK2MSFTN GP05.phx.gbl... What is the nature of the exception?
--
Get a powerful web, database, application, and email hosting with KJM
Solutions
http://www.kjmsolutions.com
"Lee Moore" <le******@hotma il.com> wrote in message
news:O3******** ******@TK2MSFTN GP03.phx.gbl...I am trying to develop a threaded function to create a dataset from an
Oracle database. When querying an elaborate view, queries take a while. I
would like to place and animated wait dialog up while the query runs. I
don't know much about threading, so bear with me. The following code
contains a class that works fine when threading is not used, but fails to
return a dataset when I execute the threading code. Any help would be
appreciate d.
Public Class QueryClass
Public QueryString As String
Public DSet As DataSet
Public TblName As String
Public Sub GetOracleDatase t()
SyncLock GetType(QueryCl ass)
Dim connectionStrin g As String =
"Provider=OraOL EDB.Oracle;Data Source=PRODUCTI ON;User
Id=myuser;Passw ord=abc123;"
Dim dbConnection As New
System.Data.Ole Db.OleDbConnect ion(connectionS tring)
Dim dbCommand As New System.Data.Ole Db.OleDbCommand
Dim dataSet As New System.Data.Dat aSet(TblName)
Dim dataAdapter As New System.Data.Ole Db.OleDbDataAda pter
DSet = New DataSet
Try
dbCommand.Comma ndText = QueryString
dbCommand.Conne ction = dbConnection
dataAdapter.Sel ectCommand = dbCommand
dataAdapter.Fil l(DSet, TblName)
Catch e As Exception
Dim logfile As New
System.IO.Strea mWriter("c:\ora cle.log")
logfile.WriteLi ne(e.Message & Chr(13) & "SQL: " &
QueryString)
logfile.Close()
MsgBox(e.Messag e & Chr(13) & "SQL: " & QueryString)
DSet = Nothing
Exit Sub
End Try
End SyncLock
End Sub
End Class
Sub DoThis()
Dim WaitForm As New dlgWait
WaitForm.Show()
WaitForm.Refres h()
Dim Qry As New QueryClass
Dim t As System.Threadin g.Thread
t = New Threading.Threa d(AddressOf Qry.GetOracleDa taset)
t.Priority = Threading.Threa dPriority.Highe st
Qry.QueryString = TextBox1.Text
Qry.TblName = "tbl"
t.Start()
If IsNothing(Qry.D Set) Then
MsgBox("No Dataset")
Exit Sub
End If
DataGrid1.DataS ource = Qry.DSet.Tables (Qry.TblName)
WaitForm.Close( )
End Sub
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