SQL Server connection sharing - Database Discussion Boards

First Prev Next

Re: sql query problem

AndyG30-Dec-01 10:45

AndyG

30-Dec-01 10:45

Try this:

select person.person_first_name, person.person_last_name, p1.position_long, p2.position_long from person inner join player on person.person_id = player.player_person_id inner join position p1 on player.player_offense_position_id = p1.position_id inner join position p2 on player.player_defense_position_id = p2.position_id

Andy Gaskell, MCSD

[ADO] leaking memory when opening/closing connection every minute

the_saw_is_the_law13-Dec-01 3:13

the_saw_is_the_law

13-Dec-01 3:13

I am developing a VB application using ADO which polls an adabas d DB and an oracle DB every minute. It seems that this programm leaks some 15mb memory every day if I open and close the connection every minute. This behaviour doesn't occur when I open the connection just once and keep it alive. Am I doing something wrong? Is this a bug? Or is this "by design"?

Michael

NT 4.0 SP5 & SP6a
VB6 SP5
MDAC 2.7
adabas d 11.01
oracle 8.1.5

code snippet:

Public gobjOraConnection As New ADODB.Connection
Public gobjOraCommand As New ADODB.Command

Dim objOraRecordSet as ADODB.RecordSet

' <connectionstring> aufbauen
strConnectionString = "DSN=" & gstrOraService & ";UID=" & gstrOraUsername & ";PWD=" & gstrOraPasswort

' Verbindung herstellen
gobjOraConnection.ConnectionString = strConnectionString
gobjOraConnection.Open

Set gobjOraCommand.ActiveConnection = gobjOraConnection

' In der Oracle DB nach Aufträgen suchen
strSQL = "SELECT * FROM " & gstrOraTable & " WHERE XCHG_RESCODE IS NULL"

gobjOraCommand.CommandText = strSQL

' Ergebnisobjekt zuweisen
Set objOraRecordSet = gobjOraCommand.Execute("adCmdText")

<doing something="" with="" the="" recordset="" here="">

objOraRecordSet.Close
set objOraRecordSet = Nothing

Set gobjOraCommand.ActiveConnection = Nothing
gobjOraConnection.Close

Re: [ADO] leaking memory when opening/closing connection every minute

Mike Osbahr13-Dec-01 10:08

Mike Osbahr

13-Dec-01 10:08

Strangely enough, I had the same problem a while ago. A colleague of mine
had a similar problem a couple of years before that. Since we both work in
C/C++ I don't know if this will help or not:

My first attempt was like this:

bar::foo() {
ADO_DB db;
ADO_RS rs;

db.Open();
...
db.Close();
}

This leaked badly. The next attempt was:

bar::foo() {
ADO_DB* db = new ADO_DB;
ADO_RS* rs = new ADO_RS;

db->Open();
...
db->Close();
delete db;
}

This leaked less, I don't know why, but still it leaked.
My working code looks like this:

class bar {
ADO_DB* mdb;
}

bar::bar() {
mdb = new ADO_DB;
}

bar::foo() {
ADO_RS* rs = new ADO_RS;

db->Open();
...
db->Close();
}

Class 'bar' is instantiated once and remains active for the life of
my program. In this final form, I can open and close the database as
often as I like. The leak as near as I can tell occurs deep within ADO.

I'm not sure about the Public declaration in VB, but it seems your
code snippet is very close to my 'working' solution. Does your variable
gobjOraConnection exist for the duration of the program's execution?

>>>-----> MikeO

Re: [ADO] leaking memory when opening/closing connection every minute

the_saw_is_the_law15-Dec-01 7:40

the_saw_is_the_law

15-Dec-01 7:40

yes, gobjOraConnection exists for the whole life of my application. There's another things I noticed: If i close the connection, the memory needed doubles from 3.5mb to 7mb and then slowly comes down again. Strange ...

Re: [ADO] leaking memory when opening/closing connection every minute

chris foote17-Dec-01 15:02

chris foote

17-Dec-01 15:02

Instead of this:

>Public gobjOraConnection As New ADODB.Connection
>Public gobjOraCommand As New ADODB.Command

Try this:

Public gobjOraConnection As ADODB.Connection
Public gobjOraCommand As ADODB.Command

set gobjOraConnection = new ADODB.Connection
set gobjOraCommand = new ADODB.Command

Late binding is supposed to help conserve memory. The theory goes that Your program doesn’t have to check to see if you made an instance to your object every time you make a call to it.

Throwing in a few set = nothings never hurts.

set gobjOraCommand = nothing
set gobjOraConnection = nothing

Good luck!

ADO with Jetengine very slow?

zack12-Dec-01 4:29

zack

12-Dec-01 4:29

We are using ADO(in a C++ env.)
to connect to diffent databases just
by replacing the provider string.

What we noticed is that the ADO/OleDB Provider for
JetEngine (4.0 and 3.51) (Access) is very, very slow.

We compared with the the ADO/OleDB Provider for
MS-SQL and we found a factor 60 !!!.

We tried with old DAO MFC - Classes with
Access-databases and the factor was 100 faster
than with ADO/OleDB with JetEngine.

Just using plain OleDB didnt make things much faster.

Do someone know more about slowliness of OleDB for
Jetengine? Are there alternative OleDB drivers
that are faster?
Confused | :confused:

zack

Re: ADO with Jetengine very slow?

Thomas Ascher8-Jan-02 1:00

Thomas Ascher

8-Jan-02 1:00

Try to use client cursors instead of the default serverside cursors if the .mdb file is on your local pc:

_RecordsetPtr pSet(__uuidof(Recordset));
pSet->CursorLocation = adUseClient;
pSet->Open(...);

SQL Server connection sharing

Nick Blumhardt11-Dec-01 15:33

Nick Blumhardt

11-Dec-01 15:33

Hi everyone Smile | :)

I'm not sure if this is possible, but I was wondering if there was a way for two threads to concurrently (and reasonably independently) share an SQL Server connection, such as the OLE DB templates CDataSource object? Presently, my attempts have been serialised internally by SQL Server, so that the net effect is that one of the requests must complete before the other can begin...

thanks to anyone who can offer some pointers!

nb

Re: SQL Server connection sharing

Rashid Thadha12-Dec-01 3:04

Rashid Thadha

12-Dec-01 3:04

One possible way of implementing this is to use ADO and ADO Events.

Basically you execute a SQl statement and once the statement has been executed, you will recieve an EVENT that the execution has completed. This will allow you to run your second sql statement. knowing the first one has finished.

see the following for example

http://msdn.microsoft.com/library/default.asp?url=/library/en-
us/ado270/htm/mdevteventmodelxvc.asp

Re: SQL Server connection sharing

16-Dec-01 18:33

thanks Rashid, I'll give it a shot.

Getting (OLE-DB) row handle

Selahattin ERDEN10-Dec-01 12:06

Selahattin ERDEN

10-Dec-01 12:06

Is there appropriate way to get active row handle from ADO recordset object(_Recordset) while it's operating in filter mode or append mode .?

Help!. Access & ODBC & Left Outer Joins

Fred C V10-Dec-01 6:38

Fred C V

10-Dec-01 6:38

I have developed some sql queries in MS SQL Server using left outer joins but the same queries does not work in access because the odbc driver does not support it. Please can anybody suggest me a workaround

Re: Help!. Access & ODBC & Left Outer Joins

AdamF4-Jan-02 5:24

AdamF

4-Jan-02 5:24

Are you sure it is the left outer joins causing the problem? I have used left outer joins in ASP pages accessing an Access database via odbc. Why not post the query.

Adam

-------
Like you will ever visit my sites...
www.ufowatch.com - Seen a UFO then report it here or view over 500 different reports.

www.clubpages.co.uk - Taking the Bournemouth club scene through the millenium

Re: Help!. Access & ODBC & Left Outer Joins

Fred C V16-Jan-02 19:43

Fred C V

16-Jan-02 19:43

Reason is that you are using ado to connect to access while i am using plain odbc.

MySQL HELP!

Bill Gates Antimatter Particle10-Dec-01 1:44

Bill Gates Antimatter Particle

10-Dec-01 1:44

Has anybody used MySQL via MFC? If so please point my in the right direction. Example code / db would be very useful.. Confused | :confused:

"Life begins at 140"

Retrieval of data from mulit table from SQL server and load into datagrid

blueei5-Dec-01 21:44

blueei

5-Dec-01 21:44

hilo, i'm a newbie at VB.NET... and i've wrote in VB.NET
i've been trying examples from reference books and online reference... but it seems that i either got the syntax wrong or just could not get it right, i think that i have something somewhere wrong with the Join table part. as i have to use 3 different tables to get the result.
anyone, pls help out... thank you! veri veri much! Blush | :O

my syntax are as follows...
'''''''''''''''''''''''''''''''''''''''''''''''''''
Dim objDataSet As New DataSet("ValidReasonList")
Dim cnn As SqlConnection
Dim cmd As SqlDataAdapter
Dim sql As String
Dim tblValidReasons As New DataTable("ValidReasons")

cnn = New SqlConnection("server=(local); database=sas2000; Integrated Security=SSPI")

sql = "SELECT A.APPROVED, B.ADMNO, B.DATEFROM, B.DATETO, B.REASON_DESC, C.REASONTYPE_NAME"
sql = sql & "FROM ABSENCE A, ABS_REASON B, ABS_REASON_TYPE C"
sql = sql & "WHERE A.REASON_ID = B.REASON_ID AND B.REASONTYPE_ID = C.REASONTYPE_ID"
sql = sql & "ORDER BY B.ADMNO"

cmd = New SqlDataAdapter(sql, cnn)
cmd.Fill(objDataSet, "JoinTable")
dgValidReasons.DataSource = objDataSet.Tables("JoinTable").DefaultView
dgValidReasons.DataBind()
'''''''''''''''''''''''''''''''''''''''''''''''''''''' Rose | [Rose]

Allow Zero Lenght and SqlAPI

4-Dec-01 6:20

Hi
I have Access Database.
How to set property of TextField - <strong>"Allow Zero Lenght"</strong> using only <strong>SqlAPI</strong>?

Thanks,
iLYA
http://www.terra-informatica.org/ilya/prnsniff.htm
Cool | :cool:

ideas please

Djibril3-Dec-01 18:50

Djibril

3-Dec-01 18:50

Hello,
I am new to database programming (actually, I am not started yet).
I am recording some data in real-time (voice). Now I need to allow the user for searching for some data given a specific time.
I was told that I should consider using SQL, or DAO or ODBC.
I have no clue what the best thing to use is. So I am looking for some information.
Any suggestion (books, articles, code, ... ) will be largely appreciated.

Thanks a lot.

Where there is a WISH, there is a WILL.

SQL Server -> Access

Michael Martin25-Nov-01 14:16

Michael Martin

25-Nov-01 14:16

I have a database created in SQL Server 7 SP3 that I want to convert to Access 2000. Is there a utility that I can use to do this or will I have to do it manually?

I have been retrenched from my job so have no access to SQL Server any more. The database is a personal one I created for myself.

Michael Martin
Australia
mmartin@netspace.net.au

"Don't belong. Never join. Think for yourself. Peace"
- Victor Stone

Re: SQL Server -> Access

Matt Gullett25-Nov-01 14:40

Matt Gullett

25-Nov-01 14:40

I do not know of any tool that can do this, and I doubt a comprehensive one exists since access does not support triggers or stored procedures. If your database uses triggers or stored procedures, you are probably out of luck on the conversion front.

On the other hand, MSDE is included with Office 2000 professional, and Visual Studio and can be used redistributed freely. It does not include the management tools (Enterprise manager, query analyzer), but there are some free ones available (I don't have a link handy, but I will look around and if I find some, will post them for you.)

Re: SQL Server -> Access

Michael Martin25-Nov-01 19:19

Michael Martin

25-Nov-01 19:19

Matt

thanks for the help. I don't have any triggers or stored procedures. I have MSDE but since I don't need the complexity of SQL Server I thought I would go to Access 2000.

Anyone else know of a tool I can use to convert?

Michael Martin
Australia
mmartin@netspace.net.au

"Don't belong. Never join. Think for yourself. Peace"
- Victor Stone

Re: SQL Server -> Access

Rashid Thadha26-Nov-01 2:43

Rashid Thadha

26-Nov-01 2:43

Use the Export (DTS) functionality on Enterprise Manager.

This works perfectly.

Two difficult ADO questions

ssteo23-Nov-01 23:21

ssteo

23-Nov-01 23:21

1. I have one Access .mdb file. How to read the names of the tables in it, using ADO

2. In the same database, how to read the description field of each column, using ADO again

Any answer will be helpfull. Thanx in advance!!!

Re: Two difficult ADO questions

Rashid Thadha26-Nov-01 2:45

Rashid Thadha

26-Nov-01 2:45

See sample here

http://www.codeproject.com/database/isqlado.asp

This has the source code that you require

Re: Two difficult ADO questions

Giles26-Nov-01 3:09

Giles

26-Nov-01 3:09

In VB for a data source named MYDB,

Dim cnn As New ADODB.Connection
Dim rs As New ADODB.Recordset
Dim i As Long, j As Long

cnn.Open "MYDB"

Set rs = cnn.OpenSchema(adSchemaTables)

Debug.Print "Number of Records ", rs.RecordCount
Debug.Print "No of Fields : ", rs.Fields.Count


For j = 0 To rs.Fields.Count - 1
    Debug.Print rs.Fields(j).Name & " ";
Next j


Debug.Print


For i = 0 To rs.RecordCount - 1
    For j = 0 To rs.Fields.Count - 1
        Debug.Print rs.Fields(j).Value & " ",
    Next j
    
    Debug.Print
    
    rs.MoveNext
Next i


rs.Close
cnn.Close

This should enumerate what tables the database contains. Its a bit like opening a recordset of what tables exist. Tables in tables......

Hope this helps.

Giles

Last Visit: 31-Dec-99 18:00 Last Update: 2-Jun-24 5:50

Refresh

ᐊ Prev 1...2443 2444 2445 244624472448 2449 2450 2451 2452 Next ᐅ

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.