منابع مشابه
Possible and Certain SQL Keys
In standard SQL database management systems primary key columns are NOT NULL by default. While NULL columns may be included in unique constraints, such constraints only ensure uniqueness for tuples which do not feature any null marker occurrences in the columns involved, and do not fulfil the same function as primary keys. In this work we investigate the notions of possible and certain keys, wh...
متن کاملDiscovery of Keys from SQL Tables
Keys play a fundamental role in all data models. They allow database systems to uniquely identify data items, and therefore promote efficient data processing in most applications. Due to this role support is required to discover keys. These include keys that are semantically meaningful for the application domain, or are satisfied by a given database instance. Here, we study the discovery of key...
متن کاملPossible and Certain SQL Key
Driven by the dominance of the relational model, the requirements of modern applications, and the veracity of data, we revisit the fundamental notion of a key in relational databases with NULLs. In SQL database systems primary key columns are NOT NULL by default. NULL columns may occur in unique constraints which only guarantee uniqueness for tuples which do not feature null markers in any of t...
متن کاملSchema- and Data-driven Discovery of SQL Keys
Keys play a fundamental role in all data models. They allow database systems to uniquely identify data items, and therefore, promote efficient data processing in many applications. Due to this, support is required to discover keys. These include keys that are semantically meaningful for the application domain, or are satisfied by a given database. We study the discovery of keys from SQL tables....
متن کاملSQL for Smarties: Advanced SQL Programming
Imagine that you get such certain awesome experience and knowledge by only reading a book. How can? It seems to be greater when a book can be the best thing to discover. Books now will appear in printed and soft file collection. One of them is this book sql for smarties advanced sql programming. It is so usual with the printed books. However, many people sometimes have no space to bring the boo...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Journal on Data Semantics
سال: 2020
ISSN: 1861-2032,1861-2040
DOI: 10.1007/s13740-020-00113-8