Closing DataReader ? : Releasing Memory

[Arsalan]

I have a function which return datareader

Public Shared Function ReturnDReader(ByVal query As String) As
OleDbDataReader
Dim Connection_String As String =
System.Configuration.ConfigurationSettings.AppSettings("strConn")
Dim conn As OleDbConnection
Dim cm As OleDbCommand
Dim dr As OleDbDataReader
Try

conn = New OleDbConnection(Connection_String)
cm = New OleDbCommand(query, conn)

conn.Open()

dr = cm.ExecuteReader(CommandBehavior.CloseConnection)

Return dr

Catch ExceptRaise As OleDbException

'ExceptRaise.Message()

Finally

cm.Dispose()

End Try

End Function

I call this function like this from Page_Load method
Dim d As Data.OleDb.OleDbDataReader

d = CodeMaster.Func.ReturnDReader("select * from employess")

DataList1.DataSource = d

DataList1.DataBind()

d.Close()


But for some reason after closing the datareader, the database is not
closing. (I'm using Access and record locking file is still there)

How do I resolve this ? [If the function's code is copied to the Page_Load
method then everything works fine, but problem occurs when this function is
in external class. the database doesnt close]

 

[Sharon]

Hi Arsalan.
I think it's a bad idea to return DataReader.
That is because the DataReader holds the connection open,
and you depend on the caller to close it.
I suggest you make a function that returns a DataView.
Sharon.

 

[Eliyahu Goldin]

Close the connection:

conn.Close();

Eliyahu

 

[Arsalan]

Good idea buddy, but you cannot close the connection and read data from
DataReader [please see the code], and as connection object is out of scope,
you cannot close it through Page_Load event.

Close the connection:

conn.Close();

Eliyahu

I have a function which return datareader

Public Shared Function ReturnDReader(ByVal query As String) As
OleDbDataReader
Dim Connection_String As String =
System.Configuration.ConfigurationSettings.AppSettings("strConn")
Dim conn As OleDbConnection
Dim cm As OleDbCommand
Dim dr As OleDbDataReader
Try

conn = New OleDbConnection(Connection_String)
cm = New OleDbCommand(query, conn)

conn.Open()

dr = cm.ExecuteReader(CommandBehavior.CloseConnection)

Return dr

Catch ExceptRaise As OleDbException

'ExceptRaise.Message()

Finally

cm.Dispose()

End Try

End Function

I call this function like this from Page_Load method
Dim d As Data.OleDb.OleDbDataReader

d = CodeMaster.Func.ReturnDReader("select * from employess")

DataList1.DataSource = d

DataList1.DataBind()

d.Close()


But for some reason after closing the datareader, the database is not
closing. (I'm using Access and record locking file is still there)

How do I resolve this ? [If the function's code is copied to the
Page_Load
method then everything works fine, but problem occurs when this function is
in external class. the database doesnt close]

 

[Arsalan]

Thanks,

Hi Arsalan.
I think it's a bad idea to return DataReader.
That is because the DataReader holds the connection open,
and you depend on the caller to close it.
I suggest you make a function that returns a DataView.
Sharon.

I have a function which return datareader

Public Shared Function ReturnDReader(ByVal query As String) As
OleDbDataReader
Dim Connection_String As String =
System.Configuration.ConfigurationSettings.AppSettings("strConn")
Dim conn As OleDbConnection
Dim cm As OleDbCommand
Dim dr As OleDbDataReader
Try

conn = New OleDbConnection(Connection_String)
cm = New OleDbCommand(query, conn)

conn.Open()

dr = cm.ExecuteReader(CommandBehavior.CloseConnection)

Return dr

Catch ExceptRaise As OleDbException

'ExceptRaise.Message()

Finally

cm.Dispose()

End Try

End Function

I call this function like this from Page_Load method
Dim d As Data.OleDb.OleDbDataReader

d = CodeMaster.Func.ReturnDReader("select * from employess")

DataList1.DataSource = d

DataList1.DataBind()

d.Close()


But for some reason after closing the datareader, the database is not
closing. (I'm using Access and record locking file is still there)

How do I resolve this ? [If the function's code is copied to the
Page_Load
method then everything works fine, but problem occurs when this function is
in external class. the database doesnt close]

 

[Eliyahu Goldin]

Take connection object out of that function scope.

Eliyahu

Good idea buddy, but you cannot close the connection and read data from
DataReader [please see the code], and as connection object is out of scope,
you cannot close it through Page_Load event.

Close the connection:

conn.Close();

Eliyahu

I have a function which return datareader

Public Shared Function ReturnDReader(ByVal query As String) As
OleDbDataReader
Dim Connection_String As String =
System.Configuration.ConfigurationSettings.AppSettings("strConn")
Dim conn As OleDbConnection
Dim cm As OleDbCommand
Dim dr As OleDbDataReader
Try

conn = New OleDbConnection(Connection_String)
cm = New OleDbCommand(query, conn)

conn.Open()

dr = cm.ExecuteReader(CommandBehavior.CloseConnection)

Return dr

Catch ExceptRaise As OleDbException

'ExceptRaise.Message()

Finally

cm.Dispose()

End Try

End Function

I call this function like this from Page_Load method
Dim d As Data.OleDb.OleDbDataReader

d = CodeMaster.Func.ReturnDReader("select * from employess")

DataList1.DataSource = d

DataList1.DataBind()

d.Close()


But for some reason after closing the datareader, the database is not
closing. (I'm using Access and record locking file is still there)

How do I resolve this ? [If the function's code is copied to the
Page_Load
method then everything works fine, but problem occurs when this

function
is

in external class. the database doesnt close]

 

[Arsalan]

Good suggestion but coding everything would be tedious, is there any
alternate way to do it ??

Take connection object out of that function scope.

Eliyahu

Good idea buddy, but you cannot close the connection and read data from
DataReader [please see the code], and as connection object is out of scope,
you cannot close it through Page_Load event.

Close the connection:

conn.Close();

Eliyahu

I have a function which return datareader

Public Shared Function ReturnDReader(ByVal query As String) As
OleDbDataReader
Dim Connection_String As String =
System.Configuration.ConfigurationSettings.AppSettings("strConn")
Dim conn As OleDbConnection
Dim cm As OleDbCommand
Dim dr As OleDbDataReader
Try

conn = New OleDbConnection(Connection_String)
cm = New OleDbCommand(query, conn)

conn.Open()

dr = cm.ExecuteReader(CommandBehavior.CloseConnection)

Return dr

Catch ExceptRaise As OleDbException

'ExceptRaise.Message()

Finally

cm.Dispose()

End Try

End Function

I call this function like this from Page_Load method
Dim d As Data.OleDb.OleDbDataReader

d = CodeMaster.Func.ReturnDReader("select * from employess")

DataList1.DataSource = d

DataList1.DataBind()

d.Close()


But for some reason after closing the datareader, the database is not
closing. (I'm using Access and record locking file is still there)

How do I resolve this ? [If the function's code is copied to the
Page_Load
method then everything works fine, but problem occurs when this function
is
in external class. the database doesnt close]

 

[Rob Nicholson]

I think it's a bad idea to return DataReader.

That is because the DataReader holds the connection open,

That depends upon his application really. Nothing wrong as such as long as,
as you say, it's closed correctly.

DataReader's are supposed to be fast but for small data sets, I've not found
much difference between a DataReader and a DataSet,

Rob.