During the current Covid-19 pandemic, it is necessary to have facilities track community activities make easier cope with pandemic situation which still a threat community. Contact tracing application (Contact Tracing) one solution that can be used in this regard. By utilizing Tracing, people's recorded when traveling meet other people so they generate history someone if of them infected Covid-...

Standard SQL is incapable of handling recursive database queries and nested relations. A proposed solution to allow recursion in SQL was given in SQL KC93], while a solution to allow nested relations in SQL was given in SQL=NF RKB87]. However, these two problems with SQL were handled separately, and an extended SQL that handles both recursive queries and nested relations is still lacking. To ov...

NoSQL databases support semi-structured data, typically modeled as JSON. They also provide limited (but expanding) query languages. Their idiomatic, non-SQL language constructs, the many variations, and the lack of formal semantics inhibit deep understanding of the query languages, and also impede progress towards clean, powerful, declarative query languages. This paper specifies the syntax and...

SQL-on-Hadoop, NewSQL and NoSQL databases provide semi-structured data models (typically JSON based) and respective query languages. Lack of formal syntax and semantics, idiomatic (nonSQL) language constructs and large variations in syntax, semantics and actual capabilities pose problems even to database experts: It is hard to understand, compare and use these languages. It is especially tediou...