I am working in a company that is about to start a web project. However, at this stage we are not sure about the database type. We may even let potential app user decide what database to use. Until than I have to start with something.
So lets imagine I need to consider MySQL(i), MSSQL, SQLite or similar. What approach would be best in order to be able to switch to different database via simple config file update? Is that PDO or what?
Thank you.
Different DBMS systems using different SQL syntax. For example, explore theme of LIMIT in MySQL, PostgreSQL, MS SQL Server. So, you may use abstraction above SQL. Use one of query builders or ORM library. Your choose will depend on architecture of your project.
PDO advantage is being compatible with most database.
If you ever decide to change database type, you won't have to change your code, just the connection.
Related
well for example you have build a program, for restaurant, for a cinema, wherever,
now how do you do when, you install your application, the database was installed correctly too? i dont sure but i believe this is a different database? for example a file?
(talking about sql).
and how different are going to be the queries? cuz i believe i am not going to have the same function on sql server than a file database
and what connection i shall use?
could i use entity framework?
and how capacity could to have the different file for databases?
regards
You can use a file-based database like SQLite that supports SQL queries. There are ADO adapters available as well. The link should take care of the rest of your questions as well.
Well, since you usually have absolutely no knowledge about target environment, user must configure program to his envronment at install time, or later (af first launch for example, this is much simplier than implement same functionality in installer). User specifies SQL server address (if we are talking about server-based systems) and database name he wants to use. Then database is created programmaticaly using that information.
I'm currently developing a Node.js app that needs to be able to switch between PostgreSQL and SQL Server databases. Both databases have identical tables and the operations will also be identical (basic CRUD, nothing fancy).
I've done research, and know that there are enough libraries around to access both databases.
Ideally I'd like to use a ORM and just let that handle the differences. However, I can't seem to find an ORM framework that does both. In fact, I can't locate any ORM that supports SQL Server, while almost all support Postgres.
So my question: is there an ORM that supports both? And if there isn't, are there other abstraction tools/frameworks around that will make my developer life easier?
There is a certain amount of YAGNI here, but if you are unable to find an ORM that supports both, your next best bet is to just use an Adapter Pattern and ensure you're not using the ORM directly in your code, but through a wrapper. Then if / when you need support for SQL Server, you can create the implementation for the wrapper which will replace the PostgreSQL implementation.
We have Delphi XE2. We are looking for a database for our application. We have tried Absolute Database and it supports most of SQL commands we need. I see most of Delphi users choose Firebird but it seems to hard to work with. I am so much confused about databases and licenses. Here are my problems:
When we choose a database, let's say Absolute Database, Firebird, MySql embedded etc. and if we have for example 3.000 customers, do we still need to pay to Database developers? Or is it one time fee? I am so much confused because they say when we buy, we can use it inside our building ( http://www.componentace.com/order/licenses.php ). But when we release our software, our customers will need to use the same database of course.
Absolute DB is easy to install and supports most of SQL queries. Firebird does not support most of SQL queries. Is this correct?
When we try to use Firebird, we use FlameRobin to design database. But when we try to connect using IB components, it says "Unable to connect database".
Thank you very much...
Firebird has no licensing fees at all. However, it's smart to help maintain this great project once you rely on it. There is a lot of ways to help Firebird project:
http://www.firebirdsql.org/#consider-your-contribution
Not correct. Firebird is very powerful and supports most SQL standards plus a great SQL extensions for stored procedures and triggers
Check your database connection string. It's usually something like server_ip:full_db_path if you're connecting over a network, or just full_db_path if local. You can always use an ALIAS in place of full_db_path. Make sure you have Firebird server running or, if using embedded, if it's installed correctly. Firebird has a great and very complete documentation and one of the best support groups on open source projects.
It depends on database. Absolute Database is embedded database, everything is included in your exe. Most database engines however are standalone, so they are installed as applications. It looks like if you buy commercial Absolute Database licence, no royalties are needed: http://www.componentace.com/order/order_product.php?id=8
Firebird supports most SQL standards. According to this answer, most SQL compliant embedded database is Firebird: Which embedded database has maximum SQL compliance, and concurrency support?
You must have some configuration issues with IB components, hard to say more without more information. On the otherhand, IB components are for Interbase, so you might find something else better, like UIB.
If you'll choose Firebird, then take a look at IBExpert. This is absolutely the best administration tool available for Firebird. But not cheap. =(
You should also look at Interbase, also marketed by Embarcadero, the Delphi vendor. Interbase is not the same thing as Firebird, which is probably why the IB components you mentioned didn't work.
Yes, each customer will usually have to purchase the IB database. However, there are additional choices with Interbase, depending on how you structure your application. Check how they work and see if they can fit better with what you are trying to do.
Our client wants to support both SQL Server and Oracle in the next project. Our experience comes from .NET/SQL Server platform. We will hire an Oracle developer, but our concern is with the DataAccess code. Will NHibernate make the DB Engine transparent for us? I don't think so, but i would like to hear from developers who have faced similar situations.
I know this question is a little vague, because i don't have Oracle experience, so i don't know what issues we will find.
You can easily use NHibernate to make your application database-agnostic by following some basic practices:
Design your object model first.
Do not use any database-specific code. You need somebody with good C# experience, not an Oracle developer. Do not rely on stuff like triggers, stored procedures, etc.
Let NHibernate generate the DB schemas at least initially (you can tweak things like indexes later) It will choose the best available datatypes for each DB.
Use a DB-agnostic POID generator (hilo or guid) instead of sequences or identity.
Try to avoid using SQL. HQL and Linq work fine in 99% of the cases.
Avoid NH features that are not supported by all of your target DB (for example, Future, MultiCriteria, etc)
NHibernate has a great community. You can always ask your questions in http://groups.google.com/group/nhusers besides posting here.
There are three things to consider - the ISession object, the SQL queries that are generated and your plain-old-clr-objects that are mapped to tables.
NHiberante will generate the required SQL queries based upon the chosen database dialect. If you configure NHibernate to use the SQL Server dialect it will generate SQL server correct SQL statements. This can easily be configured dynamically at runtime based on configuration.
You also need to configure your session to connect to the right type of database. Again, various configuration methods can support dynamic ISession creation at runtime.
Your actual data objects which are mapped to tables should not need to change based on database choice. One of NHibernates strengths is flexibility it provides in supporting multiple databases via a (fairly) simply configuration change and some up-front architectural thought.
See http://codebetter.com/blogs/karlseguin/archive/2009/03/30/using-nhibernate-with-multiple-databases.aspx for some examples of how you might abstract the underlying database away from the creation and usage of NHibernate.
I have been working on VB6 database desktop programming, but now a client is asking for a
simple web interface (some inserts into SQL Server db used by a desktop application).
The question is: Which approach is better?
1)creating asp.net project, connected directly to the SQL Server database;
2)creating separate (simple) mysql database managed by php and synchronization (in 15 minutes for example)
Thanks.
Personally since you already have the SQL Server database, I see no reason whatsoever to add the complexity of another database and then synchonization. The first alternative is simpler to create and can be secure if you design it correctly. The issue about hosting is irrelevant since you are going to your own database that already exists, so is the issue about cost since the databse is already there. Further since you are already supporting SQL Server, you may be able to reuse some code rather than write new code (mysql's version of SQL is not the same as SQl Server's version). Synching the two databases may be more complex than you think (differnt data types, etc.) and the data in the real database is not real-time whereas with the first alternative it is.
I'd prefer the separate database approach.
It's more secure.
PHP/Mysql hosting is widespread
You can pretty much achieve anything with the technologies available, it just depends on your skill and productivity with specific technologies and the availability of online help. Plus Microsoft stuff you tend to have to pay for whereas PHP/MySQL is totally free.