“…Indeed, research on visual query formulation is longstanding; however, early approaches such as QBE (Query by Example) [189], QBD* (Query by Diagram) [4], Visionary [15], TableTalk [61], HVQS [41], VKQS [153], VISUAL [9], X-VIQU [43], Xing [62] and XQBE [26] employ database schemas, object-oriented models, semistructured models (e.g., XML), proprietary graph-based models, etc. Experimental research shows that approaches that rely on logical models (e.g., database schemas) are not as effective as conceptual approaches, where interaction is in terms of real world concepts [154].…”