I need a method that will let me keep my MSaccess database open throughout the application operation instead of opening and closing everytime i enter data.
Currently Dim provider As String Dim dataFile As String Dim connString As String Dim myConnection As OleDbConnection = New OleDbConnection Dim cmd As New OleDbCommand
is public declared in each form . And the following is declared on private class
provider = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source="
dataFile = "C:\Program Files (x86)\SACCO\SACCO_DB.accdb"
connString = provider & dataFile
myConnection.Open()
Dim str As String
str = "INSERT INTO STAFF([ID_NO],[FULL_NAME],[EMAIL],[PASSWORD]) Values(?,?,?,?)"
Dim cmd As OleDbCommand = New OleDbCommand(str, myConnection)
This makes my application slower. Kindly, may someone guide me on how i will keep the database open on startup and closed on exit.
yes, this is a long time known issue - and we see near weekly postings about how LARGE delays can occur when opening the database. So for that 20+ years on a NEAR DAILY basis, from Access Front ends to back ends, the solution has been to force + keep a persistent connection. I can make a long post about how and why this occurs, but it has to do with the windows file system - and thus a open of the file, and Access attempting to open exclusive as it attempts to flip the use of the file into high speed single user mode can cause REALLY large delays. As noted, force and to keep the connection open is the near daily advice we see here for close to 20 years.
So, ok, we now using vb.net?
Simply declare a global var in a standard code module as public. Then in your startup code, you can do 1 of two things:
Open the database object - that means you don't have to know ahead of time to "pick" a particlar table to open.
eg this:
Imports System.Data.OleDb
Module MyGlobalCode
Public gDBCon As OleDbConnection ' global connection object
Public Sub GlobalOpenDatabase()
gDBCon = New OleDbConnection(My.Settings.TESTAce)
gDBCon.Open
End Sub
Public Sub GlobalCloseDatabase()
gDBCon.Close()
End Sub
End Module
So, now in any and all code? You use the above gDBCon and you:
Don't have to create a new connection object over and over.
You eliminate this LONG time known slow opening issue.
Now, it not clear why this big delay does NOT occur on some networks and setup - but, if it is occurring, then the above will show spectacular improvements in performance. Often the issue is even virus scanning software, and sometimes it seems to do with Active Directory. And other times, it has to do with VERY slow file creating times (each time you open the database, a ".ldb" file is also created - the time to create this file can be quite long on some systems - again a forced open connection will eliminate your software speeds being limited by external forces such as AD, or virus software, or a good number of other issues that causes this issue.
Related
Dim cat As New Catalog()
Dim con As New OleDbConnection()
Dim cmd As New OleDbCommand
Dim ds1 As New DataSet
Dim conn As ADODB.Connection
' Open the Access database.
conn = New Connection
conn.ConnectionString =
"Provider=Microsoft.Jet.OLEDB.4.0;" &
"Data Source=" + openExcel + "\Test" + ".mdb; Persist Security Info=False"
con.ConnectionString =
"Provider=Microsoft.Jet.OLEDB.4.0;" &
"Data Source=" + openExcel + "\Test" + ".mdb; Persist Security Info=False"
conn.Open()
xlWorkSheet1.Columns(5).Insert
Dim cellValue As String = ""
Dim newValue As String = ""
Dim sh1 As String = ""
Dim qty As String = ""
Dim matchText As String = ""
Dim sql As String = ""
con.Open()
sh1 = LTrim$(xlWorkSheet1.Cells(i, 1).Text)
sql = "SELECT Num_ber, Q_ty FROM good WHERE Na_me LIKE 'staff%' And Ty_pe = 'ORD'"
Dim cmd As New OleDbCommand(sql, con)
Dim myReader As OleDbDataReader = cmd.ExecuteReader()
conn.Execute(sql)
myReader = cmd.ExecuteReader() ' HERE'S THE PROBLEM
xlWorkSheet1.Cells(1, 5) = myReader.GetString(0)
xlWorkSheet1.Cells(1, 11) = myReader.GetString(1)
myReader.Close()
conn.Close()
conn = Nothing
**I wanted to retrieve a specific value from mdb and then write it to excel.
Here's my code, I got this error so many times and I can't find it out. Can anybody help me? Thanks.**
[1]: https://i.stack.imgur.com/6Fuvg.png
Ok, you first have to decide when usng .net what "provider" you are going to use, AND THEN decide what kind of data objects you want to use.
You can use a oracle provider, a sql server provider, or in this case, since we using Access, then we can use EITHER oleDB, or ODBC. Either choice is fine. Most use oleDB providers for Access, but often ODBC is a good choice, especially if down the road you plane to swap out Access for say SQL server.
What the above means in plain English?
You don't want to adopt the external ADODB code and library. That code is NOT .net, and thus you REALLY but REALLY do not want to write your .net code that way. ADODB was written LONG before .net, and is what we call un-managed code (non .net). I strong, but strong suggest you do NOT add a reference to ADODB to your project, and I beyond strong recommend you avoid introduction of a non .net library for doing this!!! We certainly can adopt the oleDB provider in .net, but we will NOT have a direct reference to JET/ACE (the access database engine) in our applcation. As noted, there are some exceptions to this suggesting, but they don't apply to you and here.
Next up:
The design pattern in .net is to create the connection, get the data, and CLOSE the connection. This "pattern" will then be 100% sure that the data base is always closed, and you NEVER have to worry about if the connection is open, closed, or even if you forgot to close the connection!!! So, do this correct, and some "open" connection will never bite you, or will you have to worry about this issue.
You can in some operations keep the connection open for performance, but lets learn to walk before we run so to speak.
next up:
We certainly do NOT want to place and have connection strings all over in our code. Not only is this going to wear out your keyboard, but if you ever need to change the connection, then you going to have to hunt down all that code.
Best to let Visual Studio save that connection in ONE location, and MORE important MANAGE this for you!!!
Next up:
Do you ONLY need to work with mdb files, or do you plan/need to work with accDB files? This is a HUGE issue, and one that you cannot ignore.
next up:
Are you going to use the x32 bit version of the Access database system, or the x64 bit version?
Since your example posted code uses JET (access data engine for mdb files ONLY x32 bit version)?
Then this ALSO means you MUST (and I repeat MUST) force your .net project to run as x32 bits. You cannot use "any cpu", and you cannot use x64 bits, you MUST choose x86 bit size for your .net project. Failure to do so will result in the project not working.
Ok, with the above information?
First up, force/set/be 100% sure your project is set to run as x32 bits.
That setting is this one:
and remove the reference you have to ADO if you created one.
Ok,
next up:
Create the connection to the database.
Project ->properties.
This here:
And then:
and then
Now, you can browse, and select the access mdb file.
But, you MUST not skip the next step - you have to choose JET (older, mdb files), or choose the newer ACE (for accDB format files).
So, this:
now this:
As noted, you choose JET or ACE here.
now, we have this and you can use test connection.
BUT BE VERY careful!!!!
If you are using vs2022, then keep in mind vs2022 is the FIRST version of VS that is now x64 bits. As a result, vs can't pass the test connection!!! Your connection is in fact ok, but will fail with vs2022.
If you using a previous version of VS (before 2022), then the test connection button should work. and you see this:
Ok, now that we have a valid working conneciton setup, we can now write code, and we will NOT use ADODB!!!!
The typical code pattern to read and load a data table (like a access VBA recordset) will be like this:
Now, I became RATHER tired of writing that same using block over and over. So, in a global module, I have this code now:
Public Function MyRst(strSQL As String) As DataTable
Dim rstData As New DataTable
Using conn As New OleDbConnection(My.Settings.AccessDB)
Using cmdSQL As New OleDbCommand(strSQL, conn)
conn.Open()
rstData.Load(cmdSQL.ExecuteReader)
End Using
End Using
Return rstData
End Function
So, now with the above handy dandy helper routine?
Your code becomes this:
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Dim Sql As String =
"SELECT Num_ber, Q_ty FROM good WHERE Na_me LIKE 'staff%' And Ty_pe = 'ORD'"
Dim rstData As DataTable = MyRst(Sql)
Debug.Print("Na_me is " & rstData.Rows(0).Item("Na_me"))
End Sub
Or, display all return rows from that data table
Debug.Print("Na_me is " & rstData.Rows(0).Item("Na_me"))
For Each OneRow As DataRow In rstData.Rows
Debug.Print("na_me = " & OneRow("Na_me"))
Next
So, you really don't need (or want) a reader anyway. Just load the results into a nice clean, easy to use data table, and from that you can loop the table, grab rows, or do whatever you want.
I am developing a VB.NET update system for a volunteer organisation’s MS Access database. The database is protected by a password as it contains personal information. I have created the application using the VB designer. I need to be able to code the application so that, if the owner decides to change the MS Access password, they will have no need to come back to me to change the code and rebuild the solution. In other words, I do not want the password to be hard coded in the app.config file or the settings.designer.vb file. My code should not need to know the password as a simple call to one of the Fill functions can test any password entered by the user. My problem is that I have found no way to alter the connection string that is tested in the setttings.designer.vb code whenever the database is accessed. I am using Visual Studio 2017.
I have spent a long time searching the web for answers and have tried various solutions involving the configurationmanager without success. I am new to this area so I would be most grateful if anyone here can help.
Here is my latest attempt which still produces an invalid password error even though the third debug statement suggests that the connection string, including the password, has been correctly set.
Public Sub UpdateConnString(connString As String)
Dim configFileMap As New ExeConfigurationFileMap()
Dim config As Configuration = ConfigurationManager.OpenExeConfiguration(configFileMap.ExeConfigFilename)
Dim connStringName As String = "TestConnectionString"
Debug.Print("0 " + config.ConnectionStrings.ConnectionStrings(connStringName).ConnectionString)
config.ConnectionStrings.ConnectionStrings(connStringName).ConnectionString = connString
Debug.Print("1 " + config.ConnectionStrings.ConnectionStrings(connStringName).ConnectionString)
config.Save(ConfigurationSaveMode.Modified, True)
Debug.Print("2 " + config.ConnectionStrings.ConnectionStrings(connStringName).ConnectionString)
End Sub
Just because a connection string is stored in the config file, you aren't required to use it as it is. You can read in that default value and then edit it before using it, e.g.
Dim builder As New OleDbConnectionStringBuilder(My.Settings.DefaultConnectionString)
builder.DataSource = dataSource
Dim connectionString = builder.ConnectionString
You can add or modify any part of a connection string you want that way at run time.
Thank you for your response. Unfortunately, the code throws a compilation error - "DefaultConnectionString is not a member of My.Settings".
Fortunatley I have now managed to find a working solution:
'My.Settings.Item("TestConnectionString") = connectionString
I'm working on a simple billing program for my father in law and the Access database is not updating. I built the connection and query inside of a try catch block but the database still won't update outside of it. I know it's probably something simple but I just can't see it. What am I missing?
'Database Connection
Dim Connection As String = "Provider=Microsoft.Jet.OLEDB.4.0; User ID=Admin; Data Source =MBPDatabase.mdb;"
Dim MBP As New OleDb.OleDbConnection(Connection)
MBP.Open()
Dim sqlJob As String
sqlJob = "INSERT INTO Jobs ([jobID], [jobClients], [jobName], [jobPrice])
VALUES("",#jobClients,#jobName,0.00)"
Dim Job As New OleDb.OleDbCommand(sqlJob, MBP)
Job.Parameters.Add(New OleDb.OleDbParameter("jobClients", txtClient.Text))
Job.Parameters.Add(New OleDb.OleDbParameter("jobName", txtJobName.Text))
Job.ExecuteNonQuery()
MBP.Close()
The problem is most likely the double qoute for jobID after the VALUES-keyword.
This leads to the following result (one double qoute):
...VALUES(",#jobClients,#jobName,0.00)
Change it to this (two single quotes):
sqlJob = "...VALUES('',#jobClients,#jobName,0.00)"
I am building an application that requires me to query an AS400 database up to 100 times per single use.
I have functions for each of the queries right now written in the following structure.
Option Explicit On
Shared Function query1()
Dim conn as New ADODB.Connection
Dim recordSet1 as New ADODB.RecordSet
conn.open("databaseName")
recordSet1.Open("Select * From Table",conn)
Return someValue
End Function
My application runs pretty slow, around 30-40 seconds. I've done some performance profiling using the tools built into Visual Studio 2013 and noticed that repeatedly opening connections to a database is taking up a significant portion of time.
My question is, can I set a global connection variable at the top level of my routine so that I only have to open the connection once, and close it once the routine is finished with all the queries? Do you think that this would significantly speed up my application?
Something like the following:
Option Explicit On
Global conn as ADODB.Connection
conn.open(DSN = "database")
Shared Function query1(ByVal conn)
Dim recordSet1 as New ADODB.RecordSet
recordSet1.Open("Select * From Table",conn)
Return someValue
End Function
Thanks in advance for your help !
Edit MY goal is this, I need to do read data from a Remedy Database using a VB .Net app. /Edit
I am trying to read data from the AR System ODBC driver in a VS 2010 VB windows form.
I have added a connection in the data connections via , a system dsn, connection string pulled from a working excel data pull, and built a connection string based via the wizard.
I can test connection, and it comes back 'test connection succeeded'.
When I click ok and the Data connection goes to my server explorer, it expands to tables, view, and procedures and viewing/refreshing those causes errors such as:
Column 'Table_Cat' does not belong to table Tables.
Error [im00][ar system odbc driver] not supported
I am aware there is the api out there, however this has a problem in that the api acts like a login session from the client, which limits you to one login session. This not feasible for the task at hand as the user needs to remain logged into remedy, and the app I'm writing will be read only for data.
The goal is a billboard app that will display certain tickets, kind of like a stock ticker.
There will be no editing of ticket data from remedy, I just need to read the tickets and provide tallies and alerts for our helpdesk.
It seemed so easy when I sat down, but now 4 hours later and a mind numbing amount of irrelevant google results, I'm almost wondering if I'm going to have to report back that it cannot be done with out the api and creating more remedy accounts. Not having to create additional remedy accounts was part of of the request put to me.
Tags: Visual Studio 2010 BMC AR System Remedy ODBC VB.NET
Update
So I have done the code by hand and now seem a few steps forward, but still blind.
Ok, so if i export my excel query it looks like this from the dqy file
export.dqy
DRIVER={AR System ODBC Driver};ARServer=xxxxxx;ARServerPort=xxxxx;UID=xxxx;PWD=xxxx;ARAuthentication=;SERVER=NotTheServer
SELECT "EN:HelpDesk"."Company Name", "EN:HelpDesk"."Call Status", "EN:HelpDesk"."Caller Region", "EN:HelpDesk"."Next Action", "EN:HelpDesk"."Detailed Description(FTS)", "EN:HelpDesk".Device, "EN:HelpDesk"."Submitted-by", "EN:HelpDesk".Impact, "EN:HelpDesk"."Arrival Time", "EN:HelpDesk"."Call Id", "EN:HelpDesk".Market FROM "EN:HelpDesk" "EN:HelpDesk" WHERE ("EN:HelpDesk"."Call Status"<>'Closed') AND ("EN:HelpDesk"."Submitted-by"<>'nis') AND ("EN:HelpDesk".Impact='High') AND ("EN:HelpDesk".Market='DCIN') AND ("EN:HelpDesk"."Caller Region"<>'UK')
First off, these quotes look wrong to me, but it seems to work because if I leave them, executing the command doesn't fail, however it doesn't return data to my data grid view in vb.
Second the EN:Helpdesk looks odd to me but again same results as the quotes.
I have tried changing the quotes to brackets [ ] but receive errors once I do.
Here is my code:
VB Code
Imports SystemM My goal
Imports System.Data
Imports System.Data.Odbc
Imports System.Data.SqlClient
Sub Main()
Dim sql As String
Dim connectionString As String = "DRIVER={AR System ODBC Driver};ARServer=xxx;ARServerPort=xxx;UID=xxx;PWD=xxx;ARAuthentication=;SERVER=NotTheServer"
sql = "SELECT ""EN:HelpDesk"".""Company Name"", ""EN:HelpDesk"".""Call Status"", ""EN:HelpDesk"".""Caller Region"", ""EN:HelpDesk"".""Next Action"", ""EN:HelpDesk"".""Detailed Description(FTS)"", ""EN:HelpDesk"".Device, ""EN:HelpDesk"".""Submitted-by"", ""EN:HelpDesk"".Impact, ""EN:HelpDesk"".""Arrival Time"", ""EN:HelpDesk"".""Call Id"", ""EN:HelpDesk"".Market FROM EN:HelpDesk WHERE (""EN:HelpDesk"".""Call Status""<>'Closed') AND (""EN:HelpDesk"".""Submitted-by""<>'nis') AND (""EN:HelpDesk"".Impact='High') AND (""EN:HelpDesk"".Market='DCIN') AND (""EN:HelpDesk"".""Caller Region""<>'UK')"
Dim bindingSource1 As New BindingSource()
Me.SQLDS_reportresults.DataSource = bindingSource1
Dim myAdapter = New OdbcDataAdapter(sql, connectionString)
Dim commandBuilder As New OdbcCommandBuilder(myAdapter)
Dim table As New DataTable()
table.Locale = System.Globalization.CultureInfo.InvariantCulture
myAdapter.Fill(table)
bindingSource1.DataSource = table
Me.SQLDS_reportresults.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.AllCellsExceptHeader)
End Sub
Project is a windows forms with a button to activate main(), a textbox (textbox1) and a datagridview(SQLDS_reportresults).
As the code stands, this causes no errors, but my datagridview never populates. Since there are no errors, I'm inclined to think my connection is working , and that my command is being executed,making my problem lay in code, however given the funky use of quotes and en:helpdesk in the sql command, I'm also concerned that is malformed and causing the where portion to return no results.
Anyone have any suggestions / ideas?
I need a way to display these results in app, and right now I don't care how just as long as I can see some data at all.
I've been googling and looked at the vb examples in the api zip but that is not related to opening a odbc connection and I found that of little help in my research.
I almost feel like I'm missing something simple or obvious.
When i run odbcad32.exe my ar system odbc driver shows 7.00.01.02 which is what I assume is installed on everyones machines as I used the remedy install set provided to me by the IT/Software admins to build this dev box.