I am recently working with a relational database program that has been written in Excel VBA. Excel VBA was chosen as it is a default application on computers where I work and therefore everyone would be able to use the database.
As part of the database development the need has arisen to add some more tables which will only interact programmatically with the current database. In order to consider all my options I am contemplating separating this new data either as an SQLite or second excel file.
I keep changing my mind as to what would be the best route and would appreciate information from those who work with the programs.
The new database would need to perform normal database functions quickly and efficiently. Given this context what are the advantages/disadvantages of using SQLite compared with excel?
Excel is not a database! If you want to use the Office applications, use Access, it is designed for that.
If you want to use SQLite, bear in mind that there is no concurrency. So if PC1 writes to the database, and PC2 wants to do that too, the file is locked by PC1 and you will get an error on PC2.
My recommendation:
You can also install SQL Server Express, this is free, with a few terms (10 concurrent users & max 10GB db). And then store your data in your SQL server. Use Excel as an interface to collect data from the SQL Server in your Excel/VBA applications. This is a lot more scale-able then Access, let alone SQLite.
OR: If your organization doesn't allow installation of software or whatever reason, go for Access.
You can use SQLite if you have a single application on a single device. Think about mobile apps, they use SQLite for example. If you have two applications on a single device, the concurrency problem of SQLite comes around the corner. It is possible that both apps want to write at the same time, which will give you an error.
Related
I have 2 questions for which I need help.
1)
I have developed an application where in I store the files(doc,xls,etc) in database. I have used LINQ to perform insert,update and delete. I have used MS SQL. Now, the requirement is that of using MySql. Can I use LINQ wit MySql. I searchd and found that LINQ only supports MS SQL and access. If it is decided that MySql should be usued, I dont want to go back to the traditional 3tier architecture. Can NHibernate can be used with MySql?
2)
How do the blade servers perform when it has to manage a data of 500gb+ data(documents). The RAM is about 12GB. Please nedd sugggestions that if such a huge amount of data is there, is it better not to store the data(documents) in database and store it in drives on the server instead.Because I have seen that if the data is stored in database(binary format) the size does increase.
Ok, here we go
1) It is not possible to communicate with an MySQL-Database via Linq To Sql, like you mentioned it is only build for MSSQL and Access. Prefer using the EntityFramework to communicate with variable databases. It is nearly the same to work with like Linq To Sql. You can easily develop your application using an MSSQL-Database and switch to a MySQL-Database after deployment by just changing your ConnectionString and installing the MySQL-EntityFramework-Connector.
These links may be helpfull to you:
Codeproject.com - An Introduction to Entity Framework for Absolute Beginners
Stackoverflow.com - Using MySQL with Entity Framework
2) I would advise you to store your data on physical drives and set references to the stored file in your database. This is because the heavy amount of data transferred while requesting one of your documents will slow down your database for other querys that normally just would take milliseconds to be executed.
Generally, how to save application data?
In a binary file, or a database? In other words, which structure can I use?
If there is a database table, how can I select data from it?
For simple applications settings, use QSettings - it provides persistent platform-independent application settings.
For more complex data, you might want to have a look at QSqlDatabase, several databases are supported, including SQLite. To select data or, more generally, to make an SQL query, have a look at QSqlQuery.
I'd like to know the best architecture.
We have a web application running different domains. Each domain has its own MySQL database but the db structure is the same for all of them.
We have a web application for the visible part of the application.
We have a dataLogic project
We have a dataEntities project
We have a dataAccess that contains only the methods to connect to the data base.
Before we called stored procedures on a database. But we had to change it because the performance was bad. Also, the problem was that every change we made we had in a stored procedure we had to copy to every database.
We are thinking in using a WebService to retrieve the data. Every domain can call the web service with a connection string and connect its database to retrieve data. This way when we change a SQL query we only have to compile the webService and change it, we don't have to change versions on multiples domains.
Also, what do you think about the SQL queries? Since we don't want to keep using stored procedures, what is the best way to do it? Directly from code?
Thanks
T
If you have multiple Database servers you will have to make Structural changes from one DB to another one way or another. There are many tools to change Database structures. These tools will look for differences between Schema, and will either generate the SQL code for you, or do the changes by itself (it depends a lot in the tool, there are powerful ones and not so powerful ones). Please do take a look at Toad for MySql. Now, for the Data changes, you may want to replicate the data from one Database to another. This is done through Replication.
We are thinking in using a WebService to retrieve the data. Every
domain can call the web service with a connection string and connect
its database to retrieve data.
This sounds like a good idea and since you already have "dataAccess" and "dataLogic" projects, it should not be too hard to make the services.
Also, what do you think about the SQL queries? Since we don't want to
keep using stored procedures, what is the best way to do it? Directly
from code?
I don't think it is a good practice to have the SQL queries directly into your code, but it depends in a lot of things, so I would suggest Stored Procedure vs Hard-Coding the queries, or LinQ (Entity Framework 4.1).
Good luck with your project and I will take a look at this thread frequently to see what you end up doing.
Have fun!
Hanlet
I'm about to build a new personal blog/portfolio site (which will be written in ASP.NET), and I'm going to run it against a SQLite database. There are a few reasons for this:
The site will not be getting a lot
of traffic, and from what I've read,
SQLite is able to support quite a
lot of concurrent users for reading
anyway
I can back up all the content
easily, just by downloading the db
over FTP
I don't have to pay my hosting
company every month for a huge
SQL2008 database that I'm hardly
using
So, should I go for it, or is this a crazy idea?
I'm not so sure about #2 (what happens if SQLite makes changes to the file while the FTP program is reading it?) but other than that, there is no reason to prefer one DB over the other (unless one of those DBs just can't do what you need).
[EDIT] Use an online backup to create the file for FTP download. That will make sure the file content is intact.
Even better, add a page (with password) to your site which creates the file at the press of a button, so your browser can download it.
It's just fine for a low traffic site as long as it's mostly read traffic. If it were me, I'd use SQL Compact Edition instead (same benefits as Sqlite- single file, no server), just because I'm a LINQ-head and the LINQ providers are "in the box" for it, but Sqlite has a decent LINQ library and managed support as well. Make sure your hosting company allows unmanaged code, or that you use the managed port of Sqlite (don't know its current stability though).
SQLite can handle this easily - go for it.
You should check, but I think that the Express version of SQL 2008 is free of charge.
Anyway, I've been working with SQLite from .NET environment, and it works quite fine (but I haven't done any load test).
And if you're not decided yet, you still can use a LINQ provider which will allow you later to switch from one database to another without rewriting your SQL code (I think to DbLinq, for example).
If you plan to backup you database, you must ensure first that it is not used at the moment.
SQLite answer this for you:
http://sqlite.org/whentouse.html
low-medium volume = okay,
high volume = don't use it
in your case its a-ok to use sqlite
Generally, yes.
But you should be aware of the fact that SQLite does not support everything that you might be used to from a 'real' DBMS. E.g. there are no constraints like foreign keys, unique indexes and the like, and AFAIK some (more advanced) datatypes are not available.
You should check for the various limitations here and here. If you can get along with that there's no reason to not use SQLite.
A rule of thumb is that if the site can run on one server
then SQLite is sufficient. That is what the creator of
SQLite, D. Richard Hipp, said at approximately 13 min
30 secs into episode 26 of the FLOSS Weekly
podcast.
Direct audio link (MP3 file, 24 MB, 51 min 15 sec).
I'd say no. First off, I don't know who you are using for a provider, but with my provider (goDaddy), it's pretty cheap at $2.99 a month or so. I get 1 sql server db and 10 mysql dbs.
I don't know how much cheaper this can get.
Secondly, why risk it? Most provider plans include at least MySQL database. You can hook up with that.
In general, SQLite isn't meant for a high-traffic website, but it can do quite well on websites getting 100,000 hits/day or less. The SQLite org website gets more than 500,000 hits/day, and generates 2 million or more DB interactions/day ... all handled by SQLite.
Here are some things that will dramatically speed up SQLite's performance:
Index your tables
Use transactions for multiple commands instead of executing one at a time.
Learn about write-ahead logging
Do a Google search on each of the above with SQLite ... your DB performance will improve dramatically.
An SQLite DB can actually be faster than a MySQL, PostGRE, MS SQL Server DB, or other hosted server-based DBs for 2 reasons:
1). SQLite is usually stored on the same machine as the website, rather than a separate server machine, eliminating round trip network latency response times.
2.) For smaller read/write requests, the SQLite engine is executing far less code, which can also be faster.
For a smaller website, a smaller DB engine like SQLite could actually be faster and more efficient.
Are you using any SQL functionality? SUM, AVG, SORT BY, etc, if yes go use SQLite. If not, just use plain txt files to store your data. Also make sure that the database is outside the httpdocs folder or it is not web accessible.
I don't know how authoritative this is but I found this:
http://www.sqlite.org/cvstrac/wiki?p=PerformanceConsiderations
and it doesn't seem good to have a lot of connections to sqlite. This seems to be bad for the web and most applications that have more than a few users. I'm having a hard time thinking of what sqlite would be used for when you don't need that many connections. Every program I can think of needs users, lots of them sometimes, so what would I use a database for that doesn't allow that many connections? I thought about prototypes but why would I use that when I can just connect to a larger database? Embedded apps maybe?
Thank you.
EDIT: Thanks everyone. I look at the page recommended below but an confused about something:
Under appropriate uses for sqlite it has:
Situations Where SQLite Works Well
•Websites
SQLite usually will work great as the database engine for low to medium traffic websites (which is to say, 99.9% of all websites). The amount of web traffic that SQLite can handle depends, of course, on how heavily the website uses its database. Generally speaking, any site that gets fewer than 100K hits/day should work fine with SQLite. The 100K hits/day figure is a conservative estimate, not a hard upper bound. SQLite has been demonstrated to work with 10 times that amount of traffic.
Situations Where Another RDBMS May Work Better
•Client/Server Applications
If you have many client programs accessing a common database over a network, you should consider using a client/server database engine instead of SQLite. SQLite will work over a network filesystem, but because of the latency associated with most network filesystems, performance will not be great. Also, the file locking logic of many network filesystems implementation contains bugs (on both Unix and Windows). If file locking does not work like it should, it might be possible for two or more client programs to modify the same part of the same database at the same time, resulting in database corruption. Because this problem results from bugs in the underlying filesystem implementation, there is nothing SQLite can do to prevent it.
A good rule of thumb is that you should avoid using SQLite in situations where the same database will be accessed simultaneously from many computers over a network filesystem.
The Question:
I'm going to show my ignorance here but what is the difference between these two?
This is answered well by sqlite itself : Appropriate use of sqlite
Another way to look at SQLite is this:
SQLite is not designed to replace Oracle. It is designed to replace fopen().
It's good for situations where you don't have access to a "real" database and still want the power of a relational db. For example, Firefox stores a bunch of information about your settings/history/etc in an SQLite database. You can't expect everyone that runs firefox to have MySQL or postgre installed on their machine.
It's also perfectly capable of running relatively-low traffic, read-heavy websites. The performance of it is overall very good, it's more than the large majority of websites need for their traffic levels.
It's often used for embedded applications.
It can be very handy to use a database like storage when you have no access to a database service. So SQLite is used since it's just a file you store somewhere.
I also find that using SQLite is good for getting a prototype application together pretty quickly without the overhead of having a seperate DB server or bogging a development environment with an instance of MySQL/Oracle/Whatever.
Also easy to pick up and move the database to a different machine if you need to.
The iPhone uses it for call history, SMS messages, contacts, and other type of data. Like Ólafur Waage said, good for embedded applications on mobile device because it's lightweight. I have used it also on stand alone applications. Easy to use and available on most platforms.
Think about simple client or desktop apps that could make use of a db, like as a poor example, an address book. Rather than bundling a huge db engine like mysql or postgre with your deliverable, sqlite is very lightweight and easy to include with your finished app.
This FLOSS Weekly podcast episode talks with the creator of SQLite and covers among other things goes over the type of things you would use it for. Everything from file systems for mobile phones to smallish web sites.
In the simplest terms, SQLite is a public-domain software package that provides a
relational database management system, or RDBMS. Relational database systems are
used to store user-defined records in large tables. In addition to data storage and management,
a database engine can process complex query commands that combine data
from multiple tables to generate reports and data summaries. Other popular RDBMS
products include Oracle Database, IBM’s DB2, and Microsoft’s SQL Server on the
commercial side, with MySQL and PostgreSQL being popular open source products.
The “Lite” in SQLite does not refer to its capabilities. Rather, SQLite is lightweight
when it comes to setup complexity, administrative overhead, and resource usage.
For detail info and solution about SQLite visit the link below:
http://blog.developeronhire.com/what-is-sqlite-sqlite/
Thank you.
What the above two answers say. Expanding slightly on Chad Birch's answer, its teh calls to the SQLite db, and a rather poor implementation of sync() that causes FF3 to be so slow in linux.