Hello
I'm a bit confused on how one should handle exceptions. I'm currently
building an ADO.NET Windows Forms application. I've built a class for
manipulating data within the database in question. This class is used
from forms. Let's assume that there is an SQL error: this will throw an
exception. Where should I handle it? How should I handle it? What to
show when giving an error message?
Is there any "centralize d" way of handling exceptions: for example,
having a centralized exception handler catch everything, and show an
error message relative to the caught exception?
Thanks
Aug 9 '08
37  1910 
Arne,
Did you see my msdn link about the SQLException and how will you get from
the server any information as you have not even a cable to it?
Cor
"Arne Vajhøj" <ar**@vajhoej.d kschreef in bericht
news:48******** *************** @news.sunsite.d k...
Cor Ligthert[MVP] wrote:
>"Arne Vajhøj" <ar**@vajhoej.d kschreef in bericht
news:48******* *************** *@news.sunsite. dk...
>>Cor Ligthert[MVP] wrote:
Jon,
And of course nothing *ever* goes wrong with valid SQL... The database
never goes down, there are never concurrency violations, locking
problems, failing to find expected data etc.
>
As far as I know them will the SQLException ignore all of those
problems you are showing
The SQLexception is needed to check if a stored procedure or an
parameter in that does not exist.
But you are in my opinion a jerk of a developer as you are testing that
at run time.
No.
ADO.NET does not return status values.
Either it is a success all the way through or you get an
exception.
The only bad thing about the exception is that you get the
same exception type for too many different problems. I guess
that will be fixed in .NET 4.0 or 5.0 !
Can you point me where your answer is about. I don't have the idea to
have written anything about a Status.
There are only two alternatives for returning errors: exceptions and
status codes. So since .NET does not have status codes, then the
choices are somewhat limited-
>But what you wrote is in my opinion true, although you can catch with the
SQLException some information why the SQL transaction on the Server Side
went wrong.
You can, but that is very bad OOP.
> However, in my opinion a designer should fix all those
errors which are catched here fix before he gives his program in
production.
None of the problems Jon list is permanent problems. They can
happen in production even if they do not happen in test.
And even if the database server did go down under test, then I am not
quite sure what the designer should fix ? Not use a database ??
(Or catch them at client side as it is hardware dependend, I
have never seen a server, which was down, give any information)
I am not quite sure what you mean by client and server here, but
since it is about database access let us assume database client
and server.
If the database server si down, then the database client will
get an exception and need to handle it. Like Jon explained.
Arne
(a lot snipped)
>
How is a broken network connection a design time error? *Handling* the
broken network connection is a design-time issue. A program cannot
predict, prevent or flawlessly detect a broken network connection, no
matter how hard it tries. Sometimes things just go wrong as you're doing
them. Signaling that we unexpectedly cannot complete an operation is what
exceptions are *for*. Stress "unexpected ly".
How can an SQLException be given back by a Server that is not connected with
your client.? http://msdn.microsoft.com/en-us/libr...exception.aspx
What on earth is "catching with the normal exception"? Do you mean a
catch-all exception handler for "things went wrong"?
http://msdn.microsoft.com/en-us/libr...exception.aspx
Cor
Cor Ligthert[MVP] wrote:
>
(a lot snipped)
>>
How is a broken network connection a design time error? *Handling* the
broken network connection is a design-time issue. A program cannot
predict, prevent or flawlessly detect a broken network connection, no
matter how hard it tries. Sometimes things just go wrong as you're
doing them. Signaling that we unexpectedly cannot complete an
operation is what exceptions are *for*. Stress "unexpected ly".
How can an SQLException be given back by a Server that is not connected
with your client.?
An SQLException is never "given back by a server", it's raised by a class
implementing database functionality. In some cases, the SQLException
represents an error condition indicated by the server. In other cases, it
represents an error condition detected independently from the server (being
unable to connect would be one).
Surely I'm not divulging some secret here, so I can't help but wonder what
you're getting at.
--
J.
Cor Ligthert[MVP] <no************ @planet.nlwrote :
(a lot snipped)
How is a broken network connection a design time error? *Handling* the
broken network connection is a design-time issue. A program cannot
predict, prevent or flawlessly detect a broken network connection, no
matter how hard it tries. Sometimes things just go wrong as you're doing
them. Signaling that we unexpectedly cannot complete an operation is what
exceptions are *for*. Stress "unexpected ly".
How can an SQLException be given back by a Server that is not connected with
your client.?
http://msdn.microsoft.com/en-us/libr...exception.aspx
Why not give it a try? That's what I've just done. Here's the exception
I received:
System.Data.Sql Client.SqlExcep tion: A network-related or instance-
specific error occurred while establishing a connection to SQL Server.
The server was not found or was not accessible. Verify that the
instance name is correct and that SQL Server is configured to allow
remote connections. (provider: SQL Network Interfaces, error: 26 -
Error Locating Server/Instance Specified)
Satisfied now?
What exception do *you* think occurs (at the client side) when a SQL
database can't be reached?
--
Jon Skeet - <sk***@pobox.co m>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com
From the top of the page from which I have sent you the link.
The exception that is thrown when SQL Server returns a warning or error. This class cannot be inherited.
So please tell Microsoft that they are wrong not me
Cor
"Jeroen Mostert" <jm******@xs4al l.nlschreef in bericht news:48******** *************@n ews.xs4all.nl.. .
Cor Ligthert[MVP] wrote:
>
(a lot snipped)
>>>
How is a broken network connection a design time error? *Handling* the
broken network connection is a design-time issue. A program cannot
predict, prevent or flawlessly detect a broken network connection, no
matter how hard it tries. Sometimes things just go wrong as you're
doing them. Signaling that we unexpectedly cannot complete an
operation is what exceptions are *for*. Stress "unexpected ly".
How can an SQLException be given back by a Server that is not connected
with your client.?
An SQLException is never "given back by a server", it's raised by a class
implementing database functionality. In some cases, the SQLException
represents an error condition indicated by the server. In other cases, it
represents an error condition detected independently from the server (being
unable to connect would be one).
Surely I'm not divulging some secret here, so I can't help but wonder what
you're getting at.
--
J.
Why did you try it, you was so sure of yourself.
But did you try the normal exception to see of this would not give almost
the same result in this not normal case.
My expirience is like that.
Cor
"Jon Skeet [C# MVP]" <sk***@pobox.co mschreef in bericht
news:MP******** *************@m snews.microsoft .com...
Cor Ligthert[MVP] <no************ @planet.nlwrote :
>(a lot snipped)
>
How is a broken network connection a design time error? *Handling* the
broken network connection is a design-time issue. A program cannot
predict, prevent or flawlessly detect a broken network connection, no
matter how hard it tries. Sometimes things just go wrong as you're
doing
them. Signaling that we unexpectedly cannot complete an operation is
what
exceptions are *for*. Stress "unexpected ly".
>How can an SQLException be given back by a Server that is not connected
with
your client.?
http://msdn.microsoft.com/en-us/libr...exception.aspx
Why not give it a try? That's what I've just done. Here's the exception
I received:
System.Data.Sql Client.SqlExcep tion: A network-related or instance-
specific error occurred while establishing a connection to SQL Server.
The server was not found or was not accessible. Verify that the
instance name is correct and that SQL Server is configured to allow
remote connections. (provider: SQL Network Interfaces, error: 26 -
Error Locating Server/Instance Specified)
Satisfied now?
What exception do *you* think occurs (at the client side) when a SQL
database can't be reached?
--
Jon Skeet - <sk***@pobox.co m>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com
Cor Ligthert[MVP] <no************ @planet.nlwrote :
Why did you try it, you was so sure of yourself.
So that I would be able to show the exact wording, as you seemed to
reject my assertion so completely.
But did you try the normal exception to see of this would not give almost
the same result in this not normal case.
My expirience is like that.
What do you mean by "try the normal exception"? Do you mean catching
just "Exception" ? Yes, of course that will catch it. But let's look at
the first post I responded to in this thread:
<quote author="Cor">
I don't know if it was just speaking words, but an SQL exception should
only be in design time, because it catches the errors you have made in
your scripts.
</quote>
That's what I was disputing. There are various reasons why you may see
a SQL exception at execution time. SQL exceptions are to indicate
database errors, and those can occur for reasons other than "errors you
have made in your scripts" - and even errors in SQL may only be visible
in certain situations.
--
Jon Skeet - <sk***@pobox.co m>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com
Cor Ligthert[MVP] wrote:
From the top of the page from which I have sent you the link.
The exception that is thrown when SQL Server returns a warning or error.
This class cannot be inherited.
So please tell Microsoft that they are wrong not me
The MSDN documentation is incomplete *and* you are wrong. I don't see how
these two exclude each other...
From the rest of the thread it's obvious that you're out to prove you're
right and the rest is wrong, even if you have to keep shifting the topic.
This discussion serves no further point, if indeed it ever served any.
--
J.
Cor Ligthert[MVP] wrote:
Did you see my msdn link about the SQLException and how will you get
from the server any information as you have not even a cable to it?
????
The exception object is created by the SQLServer ADO.NET provider
running client side, so no problem.
Arne
Cor Ligthert[MVP] wrote:
From the top of the page from which I have sent you the link.
The exception that is thrown when SQL Server returns a warning or error.
This class cannot be inherited.
So please tell Microsoft that they are wrong not me
You are completely wrong about this.
The documentation is not particular good. Whoever wrote
that must have assumed that it was obvious that no
connectivity would also result in that exception.
What else could happen ?
Arne This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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