A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> Visual query systems (VQSs) are query systems for databases that use visual representations to depict the domain of interest and express related requests. VQSs can be seen as an evolution of query languages adopted into database management systems; they are designed to improve the effectiveness of the human?computer communication. Thus, their most important features are those that determine the nature of the human?computer dialogue. In order to survey and compare existing VQSs used for querying traditional databases, we first introduce a classification based on such features, namely the adopted visual representations and the interaction strategies. We then identify several user types and match the VQS classes against them, in order to understand which kind of system may be suitable for each kind of user. We also report usability experiments which support our claims. Finally, some of the most important open problems in the VQS area are described. <s> BIB001 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> Abstract The Delaunay system supports a visual language that is specifically geared to the querying and visualization of databases. In this paper, we concentrate on the information visualization capabilities of the system. A distinctive feature of Delaunay is its full personalization capabilities: users can define their visualizations from scratch without limiting themselves to pre-defined visualization modes. Fine customization of the visualization is achieved by the availability of a visual alphabet of atomic graphical symbols and by the expressive power of the visual query language, which supports recursion. We describe the key components of the Delaunay system, namely its interface modules, which support advanced visualization techniques and principles, and its efficient constraint solver. The successful implementation of Delaunay demonstrates the feasibility of a powerful database system with which users can effectively specify a wide variety of visualizations supporting data and visualization exploration for different kinds of applications including graph visualization and business analysis. <s> BIB002 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> Recent database applications are typically oriented towards a large set of non-expert users, and therefore, they need to be equipped with suitable interfaces facilitating the interaction with the system. Moreover, the incorporation of the time dimension in database systems is a desirable feature. Indeed, several temporal data models and the corresponding textual query languages have been proposed. However, there is a limited amount of research concerning the investigation of user-oriented languages for querying temporal databases. Our proposal addresses such a need. In particular, we propose a visual query environment, namely Temporal Visual Query Environment (TVQE) which provides an easier interaction of the user with temporal databases. The system adopts a diagrammatic representation of the database schema (including temporal classes and relationships) and a "graphical notebook" as interaction metaphor. In our approach, non-database experts are released from syntactical difficulties which are typical of textual languages, and they can easily express temporal queries by means of elementary graphical operations (e.g. click on a node label). Differently from many proposals in the field of visual query languages, the language underlying TVQE is provided with formal syntax and semantics. It is based on a minimal set of temporal graphical primitives (TGPs), which are defined on a Temporal Graph Model (TGM), with visual syntax and object-based semantics. In this paper we mainly concentrate on the formal aspects of TVQE, and provide some hints on the visual interaction mechanisms and implementation issues. <s> BIB003 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> Abstract We report on an iconic interface that implements a restricted subset of SQL commands for querying a database. Database queries and the query language's tokens (verbs, adjectives, etc.) are represented by icons. To construct a query, the user composes structured iconic expressions according to the grammar of the iconic language. The language and grammar include rules for iconic construction (Quadral Composite Icons and Serial Composite Icons). In brief, the user visually queries the database by issuing structured iconic queries composed in a systematic manner. The paper describes the syntactic and semantic principles behind structured iconic expressions and the way that these principles have been implemented in an iconic interface. User evaluation is informally reported, and the role of metaphor in the design and interpretation of icons is discussed. <s> BIB004 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> The spreading of XML data in many contexts of modern computing infrastructures and systems causes a pressing need for adequate XML querying capabilities; to address this need, the W3C is proposing XQuery as the standard query language for XML, with a language paradigm and a syntactic flavor comparable to the SQL relational language. XQuery is designed for meeting the requirements of skilled database programmers; its inherent complexity makes the new language unsuited to unskilled users.In this article we present XQBE (XQuery By Example), a visual query language for expressing a large subset of XQuery in a visual form. In designing XQBE, we targeted both unskilled users and expert users wishing to speed up the construction of their queries; we have been inspired by QBE, a relational language initially proposed as an alternative to SQL, which is supported by Microsoft Access. QBE is extremely successful among users who are not computer professionals and do not understand the subtleties of query languages, as well as among professionals who can draft their queries very quickly.According to the hierarchical nature of XML, XQBE's main graphical elements are trees. One or more trees denote the documents assumed as query input, and one tree denotes the document produced by the query. Similar to QBE, trees are annotated so as to express selection predicates, joins, and the passing of information from the input trees to the output tree.This article formally defines the syntax and semantics of XQBE, provides a large set of examples, and presents a prototype implementation. <s> BIB005 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> In this poster we discuss a graphical notation for representing queries for semistructured data. We try to strike a balance between expressiveness of the query language and simplicity and understandability of the graphical notation. We present the primitives of the notation by means of examples. <s> BIB006 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> This paper introduces SEEQ - a System for Enhanced Exploration and Querying. It is a visual query system for databases that uses a diagrammatic visualization for most user interaction. The database schema is displayed as a graph of the data model including classes, associations and attributes. The user formulates the query in terms of direct manipulation as a graph of the schema objects, additional operators and constants. The output of the query is visualized as a graph of instances and constants or in some other format that is appropriate for the data. SEEQ can operate on arbitrary relational data base provided that the schema is in XML format. <s> BIB007 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> Database researchers have striven to improve the capability of a database in terms of both performance and functionality. We assert that the usability of a database is as important as its capability. In this paper, we study why database systems today are so difficult to use. We identify a set of five pain points and propose a research agenda to address these. In particular, we introduce a presentation data model and recommend direct data manipulation with a schema later approach. We also stress the importance of provenance and of consistency across presentation models. <s> BIB008 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> In contrast to a traditional setting where users express queries against the database schema, we assert that the semantics of data can often be understood by viewing the data in the context of the user interface (UI) of the software tool used to enter the data. That is, we believe that users will understand the data in a database by seeing the labels, drop-down menus, tool tips, or other help text that are built into the user interface. Our goal is to allow domain experts with little technical skill to understand and query data. In this paper, we present our GUi As View (Guava) framework and describe how we use forms-based UIs to generate a conceptual model that represents the information in the user interface. We then describe how we generate a query interface from the conceptual model. We characterize the resulting query language using a subset of the relational algebra. Since most application developers want to craft a physical database to meet desired performance needs, we present here a transformation channel that can be configured by instantiating one or more of our transformation operators. The channel, once configured, automatically transforms queries from our query interface into queries that address the underlying physical database and delivers query results that conform to our query interface. In this paper, we define and formalize our database transformation operators. The contributions of this paper are that first, we demonstrate the feasibility of creating a query interface based directly on the user interface and second, we introduce a general purpose database transformation channel that will likely shorten the application development process and increase the quality of the software by automatically generating software artifacts that are often made manually and are prone to errors. <s> BIB009 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> During the last decade, multidimensional databases have become common in the business and scientific worlds. Analysis places significant demands on the interfaces to these databases. It must be possible for analysts to easily and incrementally change both the data and their views of it as they cycle between hypothesis and experimentation. In this paper, we address these demands by presenting the Polaris formalism, a visual query language for precisely describing a wide range of table-based graphical presentations of data. This language compiles into both the queries and drawing commands necessary to generate the visualization, enabling us to design systems that closely integrate analysis and visualization. Using the Polaris formalism, we have built an interactive interface for exploring multidimensional databases that analysts can use to rapidly and incrementally build an expressive range of views of their data as they engage in a cycle of visual analysis. <s> BIB010 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> Faceted metadata and navigation have become major topics in library science, information retrieval and Human-Computer Interaction (HCI). This work surveys a range of extant approaches in this design space, classifying systems along several relevant dimensions. We use that survey to analyze the organization of data and its querying within faceted browsing systems. We contribute formal entity-relationship (ER) and relational data models that explain that organization and relational query models that explain systems' browsing functionality. We use these types of models since they are widely used to conceptualize data and to model back-end data stores. Their structured nature also suggests ways in which both the models and faceted systems might be extended. <s> BIB011 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> MashQL, a novel query formulation language for querying and mashing up structured data on the Web, doesn't require users to know the queried data's structure or the data itself to adhere to a schema. In this article, the authors address the fact that being a language, not merely an interface (and simultaneously schema-free), MashQL faces a particular set of challenges. In particular, the authors propose and evaluate a novel technique for optimizing queries over large data sets to allow instant user interaction. <s> BIB012 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> Querying databases is a common daily task carried out by a great deal of end-users who do not have specific skills in SQL language. Today, most of the database interaction is achieved by means of query interfaces provided by the database environment. However, most of these interfaces suffer from expressive limitations, since they are mostly based on metaphors that drastically restrict the expressiveness of the SQL language that is generated and executed in the background. In this paper, we present a visual interaction language and tool focused on easily querying databases by end-users. We make no assumption on the level of the user's experience with query languages, as our visual metaphor is intended for querying databases by unskilled end-users and also leveraging the restriction on the expressiveness of the queries created by them. We also report on some late braking results obtained by an experiment carried out with real users. <s> BIB013 </s> A Survey on Visual Query Systems in the Web Era (extended version) <s> Discussion <s> As usability is becoming recognized as a crucial feature for databases, there is growing reason for us to pay attention to the principles of Human Computer Interaction (HCI). This article explores the interaction of HCI with databases. We can learn from specific HCI areas, such as information visualization, from general HCI principles, such as direct manipulation, and from HCI methodology, such as running good user studies. However, there is much required for database usability that goes beyond HCI. 1 Usability in Databases Computer professionals have long recognized the importance of organizing data. The core principles of database technology were established early in the history of modern computing. Today, databases are widely used in a broad range of organizations, and are the basis for a vibrant commercial sector. In spite of these successes, there has been a longstanding question asked by many about why so much data is not in databases. In comparison, consider compilers, another computing technology whose core principles were developed early. There do remain today a few specialized situations in which people choose to write assembler directly and forgo the benefits of compiling a high level language, but these situations are rare. Why do so many choose so frequently to give up the many wonderful benefits provided by databases? Over the years, attempts have been made to address this question, most notably through object oriented databases. However, the question has not been a central concern of the database field: when there is so much growth and such great need, it is hard to devote attention to the audiences not being served well. The web has changed the situation dramatically. If you ask a non-technical person today, they will think of the web as the greatest (distributed) information store and of a search engine (like Google) as the way to (organize and) access this information. Structured databases come only much lower down in perceived importance. Furthermore, the web has democratized information, through disintermediation. When travel agents were the only users of a reservation system, they could be trained to learn magic letter codes and unintuitive access paths. But today, most of us make our own travel arrangements, without a human travel agent as an intermediary. The general user population is not willing to learn magic incantations and gets frustrated with unintuitive access paths. This democratization of database access has led to a greatly increased need for usability. Not surprisingly, usability issues have gained importance in the database community in recent years. Since usability is a central objective of the human computer interaction (HCI) community, it is natural to ask what we can learn from them. This paper examines some HCI accomplishments that relate to databases, and argues that there still remains much that we need to do beyond that. Copyright 2012 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Bulletin of the IEEE Computer Society Technical Committee on Data Engineering <s> BIB014
The arrival of the web brought with it more facilities for users to query databases. As a consequence, users expect to access easily through the web databases situated anywhere in the world. For expert users, one solution is to express queries in query languages such as SQL or XQuery. However, for novice users whose main concern is to extract data from the database but not the query languages themselves, learning SQL or XQuery is a huge task that is very far from their main concern. One solution for novice users is to hide the complexity of query languages behind a visual scenary where it is supposed that the complexity is softened with the aid of visual metaphors. This is the idea of Visual Query Systems (VQS) defined in BIB001 as "systems for querying databases that use a visual representation to depict the domain of interest and express related requests". In this paper, we have reviewed basic features of Visual Query Systems, such as the representation of databases and the representation of queries. We have also considered the feature of accessing data formatted for the web. Finally, we have reviewed two features we consider relevant to determine whether the VQSs ease querying for novel users: web availability and validation. Next, we discuss the results for each of these features. The majority of papers offer a diagrammatic representation of the database, only four papers an iconic one  BIB002 BIB003 BIB004 and one paper with form representation BIB010 . For several reasons, there are many papers whose database representation is unknown. For example, paper  hides the database and tries to guess the paths for the query from the entities chosen by the user. With respect to the query representation, the distribution is more balanced between the icon(12 papers), the diagram(11 papers) and the form (8 papers) representation. A special form of query, the faceted one, appears only in one paper BIB011 . Regarding the data format, there are 9 papers [13,28,5,1,8,23,17,?,11] out of 34 which query XML data and only two papers which query RDF data BIB006 BIB012 . The rest of the papers do not query web data. The rest of the features we have identified deal with the main question we have formulated in this paper, that is, to what extent have the VQS been the solution for novel users for querying databases? For answering this question with respect to the web availability, we can distinguish two periods. From 1997 to 2003 (see Table 2 ), when the web usage was beginning to spread, there was only one paper oriented to the web BIB002 . This was very understandable because of the time needed for reorienting the research into the new web setting. In the period 2004 to 2014, only papers BIB005 BIB010 BIB011 BIB013 propose a web implementation (see Table 3 ). Although the number of web oriented papers in this period is greater than in the 1997-2003 period, the low number of papers indicates that web orientation has scarcely been taken into account. For the validation feature, we have found a great number of papers which have only a prototype or have been tested with users in reduced experiments. Only three prototypes have been tested in real environments BIB007 BIB008 BIB009 and we have found only one commercial tool BIB010 . So, few papers go beyond testing the prototype with a few users. As a conclusion of these two features, very few papers are web oriented and also very few papers offer a prototype which has been tested in a real environment. In fact, the combination of both features is only found in paper BIB010 . Then, although the visual query systems seem to be a great idea for easing the query process for novice users, the reality is that very few papers describe real implementations. So, the answer to the main question of the paper is that, for the moment, VQSs have not been a widely accepted solution for novel users. From this observation a new, more general question arises is there any solution for easing the specification of queries? If the answer is no, novel users have to learn by themselves query languages or they have to ask computer experts for the specification of queries. In the latter case, no new research would be needed in this field. If the answer is 'we do not know', then new research is required in order to find simple visual query languages which help novice users. We strongly believe that the idea of VQSs is a good one and that the research should continue in this direction. Recent papers such as BIB014 also support the idea that a solution for naive users is not available but is necessary in this world in which the use of databases is democratized. The paper proposes as a solution visual systems in which the user writes examples of queries and the system extracts and specifies the desired query in the corresponding query language.