I'm doing a project with vb.net (smart device) on visual studio 2008 and I need to connect to a database on the device itself (I do not have a physical device to test, only emulation). How should I go about doing it? I would like the database to be in the device on start up.
I've read on the internet that you have to make a reference to System.Data.SqlServerCe but the documents are, in my opinion, vague. So, I'm pretty lost here.
So there are two questions here:
How do I deploy my database so it's there when my app starts?
How do I access that database from my app?
Both are straightforward.
A1. You have a couple options. First, understand that SQLCE databases are a single file, typically with an SDF extension. You can either package it with your app for deployment, so you know it will be there on first run, or your app can check for its existence on startup and crete the file if it's not there. If you need to populate the initial database with data (lookups, etc) then option 1 is probably better. As long as you deploy/crete the database in a persistent storage location (and under WinMo/Pocket PC that's pretty much anywhere), it will always be there when your app starts up.
A2 You are correct that you need to add a reference to System.Data.SqlServerCe, which is again straightforward. Just add a reference in your smart device project:
Once you've done that, you use the SqlServerCe namespace objects to create the database, tables, indexes, etc, insert and query data, and all of that good stuff. Tutorials 2 and 3 on MSDN here are a really good start and they have VB.NET examples. The nice thing is that most desktop examples for VB.NET accessing a SQLCE database will work as-is on the device, and the things that don't work are usually in the presentation of the data, not the actual database access code itself.
Related
I'm working on a database driven program in Visual Studio 2015, in C#, Windows Form Application, and I'm using SQL Server 2014 for my databases, downloaded the most recent version from the MSDN site.
I've got it working well. But if I want other users on other computers and different versions of Windows, this would require them to have SQL Server installed, correct?
Basically the app is used for storing current medications, moods, a mood quiz, symptoms, etc.. and I store all the results in SQL Server databases. They can be edited, deleted, etc through the program's GUI. Do the users need SQL Server installed to use this app?
If so, is there an alternative to keeping databases without having to have the SQL Server connections, or is there a way to do this without the users having to have SQL Server installed? I don't want remote connections to me, I want it standalone.
Does this make any sense? If not, I can explain more. I know way back in the days of Visual Basic 4 I was making, reading and writing databases without SQL. But that was 16 years ago. So I'm wondering what the easiest solution to this is. Thanks!
In other words, you want a database that you can a) distribute to end users freely and b) that will 'connect' just to the copy of the database they have stored locally.
Here are a few options ---
SQLite over ODBC is as-easy-to-use as MSSQL, the driver can be found here:
SQLite ODBC
Use ConfigurationManager.OpenExeConfiguration to read / write your app config .xml file and use it as a key / value store. I can provide examples if needed.
Dynamically create an Access database, it should work as well as MSSQL for most things, with less overhead. Here's how:
Create an Access Database
Use SQLIte DLL. Details on SO
create-sqlite-database-and-table
I'm fairly newb when it comes to programming and even newer when it comes to database management and integration.
So I have a VB.NET Windows Application that uses a SQL Database. I use LINQ to SQL to fill datagridviews in windows that show table data and also use LINQ to SQL to save data to the database.
All works wonderfully however...
When I publish the application, the database isn't external as far as I can tell. It seems to build itself into the application so once the application is installed, the database is there, it views and saves data, but if the computer crashes or the application is uninstalled, all that data is going to be lost without a way to back it up.
I'm using Visual Studio 2010 Express. I created the SQL Database in VS2010-Exp as well. I feel like there's something simple I'm missing here. When the application gets published and then installed, where is the physical database going?
Thanks!
It is running as part of the application. If you wanted a separate, central database, you would need to have an instance of SQL server running in some accessible location.
I have been using MS Access databases via DAO for many years, but feel that I ought to embrace newer techniques.
My main application runs on end user PCs (no server) and uses a shared database that is created and updated on-the-fly. When the application is first run it detects the absence of a database and creates a new empty one.
Any local user running the application is allowed to add or update records in this shared database. We have a couple of other shared databases, that contain templates, regional information, etc., but these are not updated directly by the application.
Updates of the application are released from time to time and each new update checks the main database version and if necessary executes code to bring the database up to the latest specification. This may involve the creation or deletion of tables and/or columns. New copies of the template databases are also included as part of the update.
Our users are not required to be computer-literate and should not need to run any sort of database management software beyond those facilities provided by the application.
It all works very nicely with DAO/Access, but I'm struggling to find how to do it with SQL Express. The databases seem to be squirrelled away in locations that are user-specific and database creation and update seems at best awkward to do by program code alone.
I came across some references "Xcopy deployment" that looks like it could be promising, but there seem to be references to "user instances" that sound suspiciously like something that's not shared. I'd appreciate advice from anyone who has done it.
It sounds to me like you haven't fully absorbed the fundamental difference between the Access Database Engine (ACE/Jet) and SQL Server:
When your users launch your Access application it connects to the Access Database Engine that has been installed on their machine. Their copy of ACE/Jet opens the shared database file (.accdb or .mdb) in the network folder. The various instances of ACE/Jet work together to manage concurrent updates, record locking, and so on. This is sometimes called a "peer-to-peer" or "shared-file" database architecture.
With an application that uses a SQL Server back-end, the copies of your application on each user's machine connect over the network to the same instance of SQL Server (that's why it's called "SQL Server"), and that instance of SQL Server manipulates the database (which is stored on its local hard drive) on behalf of all of the clients. This is called "client-server" or "server-based" database architecture.
Note that for a multi-user database you do not install SQL Server on the client machines, you only install the SQL Server Client components (OleDb and ODBC drivers). SQL Server itself is only installed in one place: the machine that will act as the SQL... Server.
re: "database creation and update seems at best awkward to do by program code alone" -- Not at all, it's just "different". Once again, you pass all of your commands to the SQL Server and it takes care of creating the actual database files. For example, once you've connected to the SQL Server if you tell it to
CREATE DATABASE NewDatabase
it will create the database files (NewDatabase.mdf and NewDatabase_log.LDF) in whatever local folder it uses to store such things, which is usually something like
C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA
on the server machine.
Note that your application never accesses those files directly. In fact it almost certainly cannot do so, and indeed your application does not even care where those files reside or what they are called. Your app simply talks to the SQL Server (e.g. ServerName\SQLEXPRESS) and the server takes care of the details.
Just to update on my progress. Inspired by suggestions here and this article on code project:
http://www.codeproject.com/Articles/63147/Handling-database-connections-more-easily,
I've created a wrapper for the ADO.NET methods that looks quite similar to the DAO stuff that I am familiar with.
I have a class that I can use just like a DAO Database. It wraps ADO methods like ExecuteReader, ExecuteNonQuery, etc. with overloads that can accept a SQL parameter. This allows me to directly replace DAO Recordsets with readers, OpenRecordset with ExecuteReader and Execute with ExecuteNonQuery.
Each method obtains and releases the connection from its parent class instance. These in turn open or close the underlying connection as required depending on the transaction state, if any. So a connection is held open for method calls that are part of a transaction, but closed immediately for a single call.
This has greatly simplified the migration of my program since much of the donkey work can be done by a simple "find and replace". The remaining issues are then relatively easy to find and sort out.
Thanks, once again to Gord and Maxwell for your advice.
This answer is too long to right down... but go to Microsoft page, there they explain how to make it: http://office.microsoft.com/en-us/access-help/move-access-data-to-a-sql-server-database-by-using-the-upsizing-wizard-HA010275537.aspx
I hope this help you!!
I am busy developing my own application, it uses a sql server database and it is connected through an entity framework. I use store procedures to insert, update, delete, select from my database.
The app works perfect on my machine even when I publish it. But my problem comes in when I try to install the app to my friend’s computer. It crashes and does not start because it cannot connect to the database.
Is there a way to publish my app with the database, without importing all the tables, store procedures and database into my friend’s pc? I just want to make it so the user just has to install the app and it works.
Your app relies on the db to work, so if you want to put it on your friends PC then you need to make the DB available somewhere, whether it be a local copy or a copy stored on a server somewhere running SQL.
How are you storing your connection string? Is it hard coded in the app or are you utilising the app.config file? To do what you're trying to do you'll need to put the connection string into the app.config file, so you can change it depending on the installation.
either that or
if you want to run your app without data, put a demo flag or something into the app.config file. Put some code into your app to check this value, if it's true then bypass the SQL code and maybe supply some demo data which is hard coded.
Does this make sense?
You could use SQL CE, but you may find it a little more difficult to 'design' your database in it if you are more used to working in SQL Server.
Have you considered SQL Server Express as an option?
On the connection string issue, you can now get the data connection wizard that Microsoft use in Visual Studio via Nuget; this makes adding a way to dynamically configure connection strings on your clients machine much easier.
Lastly, connection strings for the entity framework are different from standard SQL connection strings. Make sure that you clearly understand the differences before you start trying to configure them programmatically. Julie Lerman's excellent book on the Entity Framework explains the differences well.
I'm writing a desktop application that uses the main access database that will be hosted on a central server, but there will be a laptop with the app on that has an offline mode so records can be created offsite. When the laptop returns I want it needs to be synced back to the main database.
Has anybody got any pointers on a way to do this, I've briefly read about JRO but is there an alternative / better method?
Originally, I was just going to write some custom code to do this, but thought I'd check to make sure there wasn't something already out there.
Jet Replication is a perfect solution for this kind of scenario, because you can use the simplest form of it, Direct Replication, and don't need to have any outside dependencies.
Assuming your server is named \HomeOffice\ and the database is named "MainDatabase.mdb" and is stored in the \AccessDatabases\ folder, you could use this code behind a command button to synchronize from the laptop to the server:
Dim dbServer as DAO.Database
Set dbServer = DBEngine.OpenDatabase("\\HomeOffice\AccessDatabases\MainDatabase.mdb")
dbServer.Synchronize CurrentDB.Name
dbServer.Close
Set dbServer = Nothing
Now, there's no error handling, and you haven't checked for conflicts, so you'd need to do more than that, but that would get you started with the basics.
See the Jet Replication Wiki for lots more information on Jet Replication.
Access (at least through 2003) has built in capabilities to replicate a database that would be far better to use than rolling your own.
Here's some documentation on that feature: Database Replication
MS Sync Framework could be the answer, but it's a bit tricky to set up... http://msdn.microsoft.com/en-us/sync/bb821992
There is the Microsoft Sync Framework that is compatible with ADO.NET and MS SQL Server / SQL Server Compact, but that's not a small component, more like a multi-component framework.