为什么挡块没有被触发？

Question

I am trying to log errors to a file but I can't seem to get the catch block to run when an error occurs. Here is an example of the code:

try  
{  
     cmd.ExecuteNonQuery();  
}  
catch (MySQLException ex)  
{   
     //run some logging code  
}  
finally  
{  
     //clean up the resources  
}  

The problem is when there is an exception, I get the error thrown from the built in webserver that its an unhandled exception. When I debug the code stops at the exception then continues on to the finally block. Can someone point me in the right direction here?

Answer 1

ExecuteNonQuery() throws an exception of type SqlException .

So I'm not sure what MySQLException is, but you need to be catching an SqlException .

Look at this for extra info:

• SqlCommand.ExecuteNonQuery Method
• SqlException Class .

Answer 2

It seems like the exception thrown is not not of type MySQLException or any exception derived from it. So the catch block never never catches it and the finally block is executed directly!

To check what kind of exception was raised, modify the code to:

try  
{  
   cmd.ExecuteNonQuery();  
}  
catch (MySQLException ex)  
{   
   //run some logging code  
}  
catch (Exception ex)
{
   // any other exception will be handled here
}
finally  
{  
   //clean up the resources  
} 

Answer 3

That method can throw different types of exceptions

• InvalidCastException
• SqlException
• IOException
• InvalidOperationException
• ObjectDisposedException