I'm trying to compute statistics for data held in an Access .mdb database. In order to avoid interfering with the live database, I'm working from a copy which I made by simply using copy-paste in Windows Explorer. The copy resides in the same directory, but with a different name.
I'm using R and RODBC to connect to the copy of the file. The strange thing is that new data that is being updated on the original live database is appearing in my queries. This is despite the file timestamps of the copy not changing at all. It is also causing some slowdown in the live database.
My understanding is that the .mdb files are standalone, or is this not the case? Should I have copied the database in a different way?
It seems that you may have copied the front-end of a front-end / back-end set up. The back-end is where data is held and tables are linked to a front-end to hold forms etc. Copying a front-end copies the back-end links, so the data is live.
Related
I have lately re-discovered embedded databases such as Sqlite (sql, relational) and LiteDb (noSql) and I like working with them for small web apps or mobile apps.
However, I cannot find any good answer to where to place them. Where to put them if:
The web app is likely to be containerized
The database can grow dynamically
Changes to the code and new deployments should not risk losing any change in database
1. Database file as part of solution (versioned in source control)
I've seen places where the *.db file is placed somewhere in the solution and it's versioned in source control.
I can see how this could be a problem as the database can be modified outside the context of development (i.e: when the app is up and running in production, the DB may change and in the next deployment the db may be overwritten if no backup/restore process in place)
Sometimes I have seen it inside wwwroot/App_Data. See this for instance. I assume App_Data is some kind of protected folder and its files cannot be server statically by the web server (is it?). Otherwise this is even worse.
2. Database file in binary folder
When testing, it's fine to have the database file generated somewhere in the bin folder, but this causes a similar problem as the previous one. What happens when a new software version is released and therefore the database file is overwritten in production?
So the questions are:
Is there any good practice regarding where to place embedded database files?
Is there any alternative to having backup/restore processes to avoid the described data-loss scenarios?
What happens when the app is contenierized and the database file grows once deployed? If the file is inside a container along with the running application, can it grow indefinitely? I don't recall specifying anything about a maximum size for containers anywhere when creating images..
Is having the DB in an external storage such a cloud blob store the alternative? I'm guessing the real benefit of embedded databases is gone if the file is in a different host.
Any good read about this would be appreciated.
PS:
I am asking for AspNet Core apps mainly because I see some projects using the wwwroot folder to place the embedded DB, but the question applies to any technology/framework.
This other question doesn't help either.
I'm creating an app where users need to work with large databases. Rather than having the users download the data and populate an SQLite database on the client (which would take a long time), I'm hoping I can use downloadable, pre-populated databases.
I found cordova-sqlite-ext, which allows working with pre-populated databases, but SQLite files must be located in the www folder for this to work. Is it actually possible to download files to this folder in Ionic/Cordova (on non-rooted devices)?
It's always good practise to store your files in app's directory. Check this comment of mine and see if it helps you:
https://github.com/driftyco/ionic-native/issues/881#issuecomment-270832521
I had a requirement of downloading a zip file(with sqlite file in it), unzip the file, store the file in app's directory and query the DB. I was able to achieve it using plugins and works quite well.
I am currently using Komodo edit for coding, and have a set up where I am using MAMP and a local install of Drupal, and SASS to build my site offline.
Once its ready test online, I upload onto the remote site. However, then I am working sometimes on the remote site and sometimes on the local one, and finding some problems.
I'm not using SASS on the remote site, so I am working in the CSS file. I don't have all the Drupal panels in code yet, so I'm having to rebuild them on the remote site, and I'm making tweaks and changes on the fly.
I end up with two slightly different versions of the site and need to keep track of the changes I want to keep from both. What can I do to clean up my workflow?
It would be better if I could work entirely locally and then sync that to the remote environment.
With something like Netbeans I think I could have a local copy of the site running and then right click and upload each file onto the remote server so there are two copies of the file.
I could do with some advice as to what the cleanest set up is.
I have an actual Dev server with its own ip and a live server with its own ip but they both connect to the same mysql server. There are two databases set up, db1 and db2.
I use a php script with basic sql instructions to:
Check which db is in use.
Backup that db (say, db1).
Sync the databases
Import that db into db2.
Once that is done, I use this:
cp webdb2.settings.php settings.php
So I always have two databases available and can roll right back (in this case with:
cp webdb1.settings.php settings.php) if something when wrong.
This seems to be a pretty good system. I only ever work on the dev, and then push it to the live with the process above.
The best thing that you can do is work offline an then sync the content (themes/modules) when you have to.
If you work on both you could lose data or lose track of code changes.
I have been using a central MS SQL database located in the cloud to develop a web site project. I have recently found myself in situations, when I need to develop without the internet connection. I want to begin to use a locally available copy of the existing database, put it in App_Data folder.
What is the correct set of steps I need to undertake to get the project to work with local DB?
For example:
Detach a db from an existing SQL instance.
Copy to a development machine.
etc.
Moving a SQL-Server DB is not that hard. Look here for some methods to do it.
http://support.microsoft.com/kb/314546
I usually find the sp_detach + sp_attach method really easy.
I would create an empty shell database locally, then use one of the many schema comparison solutions available to make the local database look exactly like the cloud database.
Correct way is to create and regularly update your standalone copy of database using import/export. In particular MS SQL Server provides Import/Export Wizard tool for such purpose.
Make a backup
Copy backup file
Restore on your server
Restore/organise users
I'm working through the "Demo: Binding Data with the SqlDataSource" of this pluralsight video on ASP.NET Webforms.
All communication with the database works just fine, except it won't change when updates are made. The only thing I've done differently from the video is to use Northwind.sdf instead of Northwind.mdf. The database exists in the project directory, which is under my Users directory on win7 -- so it shouldn't be a permissions problem.
What could be preventing it from updating?
In case anyone wants to try the sample app, I uploaded the whole project folder here on mediafire.
Maybe you have two copies of the database. You are updating copy A and then checking copy B.
Or, it could be one of the reasons described here: http://weblogs.asp.net/stevewellens/archive/2009/10/16/why-sql-updates-fail-three-reasons.aspx