criteria progress

source/orm/sql/dialect.cpp

@@ -221,6 +221,14 @@ const std::string &dialect::into() const {
   return token_at(dialect_token::Into);
 }
 
+const std::string &dialect::is_null() const {
+  return token_at(dialect_token::IsNull);
+}
+
+const std::string &dialect::is_not_null() const {
+  return token_at(dialect_token::IsNotNull);
+}
+
 const std::string &dialect::join() const {
   return token_at(dialect_token::Join);
 }