Working in a VB.Net 3.5 WinForms application, and using Access 2003 (JET 4.0) as a database backend through ADO.Net.
I'd like to check the database for changes, before the application decides to refresh the data from the server. Are there any best practices for this, or should I trust the ADO.Net environment to optimise/handle this?
I was thinking of using a limited log on the server, which gets updated by every change. Pulling this log could tell whether or not a certain table has changed data. Any good?
Easiest way is to use a file based cache, which would just invalidate the cache if anything is written to the database.
This won't give you any table specific caching so this isn't the most efficient thinkable cache.
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I have a windows service which uses EF Core to save data into SQL database. The main requirement for this service is that it works even if database is unavailable. Soo, if service needs to insert data into database and database is not available it should temporary save it somewhere else and insert them later (when database is available again).
What would be the best solution for this? I'm thinking about a queue of queries that weren't executed due to database unavailability. Are there any existing solutions for this type of problems? Does EF Core already have some kind of functionality to store data in file and insert them into database, when it becomes available again? Is there maybe any other library to achieve this?
Thanks for your help!
There is a situation in my company where we are developing a light weight .net web application with least dependencies. Application will be used hosted on client server. However there will not be any internet connection and they will use application locally.
We do not want any type of database installation on client machine. We want to keep it as simple as possible on client side. for this purpose we want to save/access data from file, as data on client side will not exceed more than 100 000 rows. We are also concerned about the speed for accessing data.
Here I want to ask how the data should be saved in file so that it can be accessed fast? What file format should be?
Whether I can use any db file which does not require any database installation on client side.
You could save all data to a json file, this will become increasingly slow and prone to corruption.
Also, have a look at SqlLite.
You can try Sql Compact Edition or SqlLite. Both are file based solution and fit as per your need.
Advantage of using these two would be that you can perform almost all the database queries on it and the data retrieval will be very fast. Also the you can think of optimizing the data storage and create tables etc.
You can use SQLite which is heavily uses in such scenarios (among others used by Chrome and Firefox). It is even public domain, so no license costs etc.
I have a vb.net windows form application with a database on SQL Server 2008 on the ./SQLEXPRESS instance.
I have created a setup of my project using the link below..
http://msdn.microsoft.com/en-US/library/49b92ztk(v=vs.80).aspx
When a user installs my application, the database will be available for him, and user can just export the SQL Server database.
How can I secure my database so that user shouldn't have a easily available copy of my database?
I thought of creating a new password protected server (as I have created the database in above walkthrough)... while installation of my application on user's pc, other than ./sqlexpress. And a complete copy of database used by my application will not be simply available for user to just export and get a copy of my database.
So could anyone please guide me...
The question is; how far do you want to go to protect your data?
Better protection of your data usually comes at the cost of more development time and likely less user friendliness, for example due to lower performance (encryption is not free). More complex code usually results in more support requests too.
Where the best balance is depends on your business model (if any) and on your user requirements.
Keep in mind that anything you deploy to an end-users machine is in the end vulnerable. If something is valuable enough there will be people trying to steal it.
So, you could argue that the best protection is not to deploy the data at all. You could back your end-user application with a web service and keep the data on your own server, for example in the cloud.
I've found however that you sometimes just need to trust your users. If you build a good product that makes them happy, they have no reason to steal from you. In fact, they are probably glad to pay you.
If you decide that you need to deploy the data and that you need to encrypt it, you should think about why you chose SQL Server.
What database features do you need exactly? Do you need a fullblown database server for that?
Any local admin can gain control over any SQL Server database in seconds so the built-in SQL server authentication will not bring you a lot of benefits.
You could switch to SQLServer CE and keep the database within your application. That would make the database a lot harder to access for a regular user.
If all you're doing is looking up words, you may be better off with a different storage engine like Lucene.
Lucene is actually a search engine, so it's highly optimized for matching words or parts of words.
You can run Lucene inside your .NET application so you don't even need the end-user to install SQL Server. There is a .NET version of Lucene here.
Lucene however doesn't protect your data. There's tooling available that will allow anybody to view and extract the data from the stored index files.
Since Lucene is open source though, you could extend it to support encrypted data storage (see this related question).
I am creating a 2-tier Lightswitch application which will be deployed via ClickOnce for single-user scenarios. The database schema and the data need to be protected from access by the users.
I know that this might not be perfectly possible, but are there ANY solutions to this?
We looked at a 3rd-party tool called DbDefence, and it seemed like a perfect fit, but their redistribution licensing pricing is way over our budget right now.
Much appreciated.
No, there's no way that I know of to prevent users from viewing or even fiddling with the database schema (if they're knowledgable enough). Unless you're creating the database for them, they have to have the permissions needed to be able to create the database. Plus updates (via Click-Once) would need update permissions on the tables.
The chances are, if you did find something, that it could prevent the application from working correctly anyway.
My database must be updated at arbitrary intervals, manually, with new info to put on standart tables that don't require structural modifications. one app will update the database.
Another app, the one I will distribute (to friends and family only, but doesn't require any security feature to it, like encrypting the database) will read the database and use its data on labels, listviews, etc.
The problem is, I'm the perfect definition of full-fledged n00b at programming of any sort, and still don't know what database to use.
I thought that I should use a SQL CE (*.sdf) file, and store that database thing on an FTP. then, I could download it and get data from it everytime the "client" app runs, and certain button ("connect") is clicked.
After some hard-core googling, I found out how to connect to the sdf thing, using this connection string:
Provider=Microsoft.SQLSERVER.CE.OLEDB.3.5;Data Source=D:\Documents and Settings\Camilo\JCTM.sdf
So it connects, or at least didn't show any error.
I don't know if it's a good idea to use sdf SQL CE files as databases, if it's too hard maybe I should go for XML? what do you guys suggest, what is the easiest way to implement very simple databases in VB.NET?
By simple databases I mean:
- no search needed
- no advanced features except storing strings on tables with columns and rows
- easy to access, read, edit, etc. by different VB.NET apps
Is sdf a good idea?
I would recommend Sql Server Express Its free and can be redistributed with .net applications as part of the install process.
The challenge will be syncing the changes between the different clients. If you have access to a FTP server, you may have the ability to host a website in IIS. If you can do that you can just use webservices and read against one database instead of copying one local.
Luckily for you, you can abstract away the need to be concerned with which back-end database you use to store your data.
Technologies such as ODBC (Open Database Connectivity) and OLEDB (Object Linking and Embedding, Database) allow you to limit your concern for the backend datastore to the task of crafting your connection string. In your example, the connection string says, "I'm going to connect to a SQL Server CE database via its OLEDB provider, and it's physically located over on D:/...
Within the code, you use standard OLEDB mechanisms to access and manage the database. Because of this abstraction, you can use OLEDB providers for SQL Server, Oracle, XML, Access or comma delimited text files as your backing store if you wish, and the only change you need to make to your code is the connection string. Your choice then should be to pick the database that you have the tools and know-how to set up and manage initially.
I'd start with Microsoft Access because it has its own UI, and can play well with .NET.
You can also try the ADO.Net implementation for SQLite, which I've also found very useful.