Implementing a Generic Database Interface in C#

[Guest]

Hi all,



I am beginner in C#.
I am currently migrating a system which was written in VB .NET to C#.
In the VB program, the programmer is able to choose the DBMS between SQL Server 2000 and Oracle,
according to a configuration string stored on the Web.config file.
This way, when the programmer wants to instantiate a data reader for example, he/she uses an
interface to do the job as in the code snippet below.

 

[Miha Markic]

Hi,

The big problem is that I cannot have a method that has not a declared

datatype like in VB.

You are returining an object - just create a method that returns an object.
Anyway, your method could/should return IDataReader interface and not an
object...

 

[Daniel Pratt]

Hi Amintas Lopes Neto,

Hi all,



I am beginner in C#.
I am currently migrating a system which was written in VB .NET to C#.
In the VB program, the programmer is able to choose the DBMS between SQL Server 2000 and Oracle,
according to a configuration string stored on the Web.config file.
This way, when the programmer wants to instantiate a data reader for example, he/she uses an
interface to do the job as in the code snippet below.

<snip>

When you declare a function (in VB) like this:

Public Function CreateDataReader()

It translates it to:

Public Function CreateDataReader() As Object

That means the equivalent C# declaration would be:

public object CreateDataReader()

Of course, I would strongly recommend you declare it as:

public IDataReader CreateDataReader()

This way it's self-documenting and you aren't going to accidentally
return something the caller doesn't expect.

Regards,
Dan

 

[Paul E Collins]

Please notice that it is not mandatory to declare
the return type for the CreateDataReader() method
in VB .NET [...]
Very well, I tried to do the same in C#.
The big problem is that I cannot have a method that
has not a declared datatype like in VB.
Does anybody knows a way to work around it ?

The two types of DataReader will probably have the same public properties
and methods, so it might be an idea to have an abstract base class (or
interface) representing a DataReader, and create two subclasses that inherit
from the base class (or implement the interface). Your return type would
then be the type of the base class or interface.

P.