Changes related to following tracker items:

[2025916] ODBC binds empty string as null?
[2000408] DynamicAny non-initialized state support
[1981130] pointless comparison of unsigned integer with zero

and some refactoring.

Warning: only tested on Windows.

Data/src/AbstractExtraction.cpp

@@ -47,7 +47,9 @@ AbstractExtraction::AbstractExtraction(Poco::UInt32 limit,
 	_pExtractor(0), 
 	_limit(limit),
 	_position(position),
-	_bulk(bulk)
+	_bulk(bulk),
+	_emptyStringIsNull(false),
+	_forceEmptyString(false)
 {
 }
 
@@ -57,4 +59,16 @@ AbstractExtraction::~AbstractExtraction()
 }
 
 
+template <>
+bool AbstractExtraction::isValueNull(const std::string& str, bool deflt)
+{
+	if (getForceEmptyString()) return false;
+
+	if (getEmptyStringIsNull() && str.empty())
+		return true;
+
+	return deflt;
+}
+
+
 } } // namespace Poco::Data