Sqlite: Add unoptional value fetcher

There is now value, valueWithTransaction, optionalValue and
optionalValueWithTransaction. Sometimes you want to return
the default constructed value as default. So this is now possible.
This simplifies some code but can be even more optimal.

Change-Id: Ibbb6b5ca47803344ed646bfa257602b6db52e0fe
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/libs/sqlite/sqlitereadstatement.h

@@ -42,6 +42,7 @@ public:
         Base::checkColumnCount(ResultCount);
     }
 
+    using Base::optionalValue;
     using Base::range;
     using Base::rangeWithTransaction;
     using Base::readCallback;
@@ -62,6 +63,18 @@ public:
         return resultValue;
     }
 
+    template<typename ResultType, typename... QueryTypes>
+    auto optionalValueWithTransaction(const QueryTypes &...queryValues)
+    {
+        DeferredTransaction transaction{Base::database()};
+
+        auto resultValue = Base::template optionalValue<ResultType>(queryValues...);
+
+        transaction.commit();
+
+        return resultValue;
+    }
+
     template<typename ResultType, typename... QueryTypes>
     auto valuesWithTransaction(std::size_t reserveSize, const QueryTypes &...queryValues)
     {