Patch for better exception use -- BadQuery w/Errnum patch part 1

[Jim Wallace]

Part 1 of broken up new version of BadQuery update patches after review
by Warren.

In this case the BadQuery was being misused in this case and Warren
suggested a new exception.

See http://lists.mysql.com/plusplus/7060 for reference

Diffs are from the current svn

Index: result.h
===================================================================
--- result.h	(revision 1779)
+++ result.h	(working copy)
@@ -105,7 +105,7 @@
 	{
 		if (!result_) {
 			if (throw_exceptions()) {
-				throw BadQuery("Results not fetched");
+				throw UseQueryError("Results not
fetched");
 			}
 			else {
 				return Row();

Index: exceptions.h
===================================================================
--- exceptions.h	(revision 1779)
+++ exceptions.h	(working copy)
@@ -235,6 +235,19 @@
 };
 
 
+/// \brief Exception thrown no result set was returned in a fetch, 
+/// usually due to an error.
+
+class MYSQLPP_EXPORT UseQueryError : public Exception
+{
+public:
+	/// \brief Create exception object
+	explicit UseQueryError(const char* w = "") :
+	Exception(w)
+	{
+	}
+};
+