Unreachable code, but reachable with an exception

Compiler Warning (level 2) CS0162

Unreachable code detected

The compiler detected code that will never be executed.

Which is just saying, the Compiler understands enough through Static Analysis that it can’t be reached and completely omits it from the compiled IL (hence your warning).

_{Note : You can prove this fact to your self by trying to Step on to the Unreachable Code with the debugger, or using an IL Explorer.}

The finally may run on an Exception, (though that aside) it doesn’t change the fact (in this case) it will still be an Uncaught Exception. Ergo, the last return will never get hit regardless.

• If you want the code to continue onto the last return, your only option is to Catch the Exception;

• If you don’t, just leave it the way it is and remove the return.

Example

try 
{
    command.CommandText = sb.ToString();
    returnValue = command.ExecuteNonQuery();

    return returnValue == 1;
}
catch(<some exception>)
{
   // do something
}
finally 
{
    command.Dispose();
}

return false;

To quote the documentation

try-finally (C# Reference)

By using a finally block, you can clean up any resources that are
allocated in a try block, and you can run code even if an exception
occurs in the try block. Typically, the statements of a finally block
run when control leaves a try statement. The transfer of control can
occur as a result of normal execution, of execution of a break,
continue, goto, or return statement, or of propagation of an exception
out of the try statement.

Within a handled exception, the associated finally block is guaranteed
to be run. However, if the exception is unhandled, execution of the
finally block is dependent on how the exception unwind operation is
triggered. That, in turn, is dependent on how your computer is set up.

Usually, when an unhandled exception ends an application, whether or
not the finally block is run is not important. However, if you have
statements in a finally block that must be run even in that situation,
one solution is to add a catch block to the try-finally statement.
Alternatively, you can catch the exception that might be thrown in the
try block of a try-finally statement higher up the call stack. That
is, you can catch the exception in the method that calls the method
that contains the try-finally statement, or in the method that calls
that method, or in any method in the call stack. If the exception is
not caught, execution of the finally block depends on whether the
operating system chooses to trigger an exception unwind operation.

Lastly

When using anything that supports the IDisposable interface (which is designed to release unmanaged resources), you can wrap it in a using statement. The compiler will generate a try {} finally {} and internally call Dispose() on the object.