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General introduction
Published in Adedeji B. Badiru, Handbook of Industrial and Systems Engineering, 2013
The idea that database systems should present the user with a view of data organized as tables called relations was originally proposed by Codd (1979). Each relation is made up of attributes. Attributes are values describing properties of an entity, a concrete object in its reality. Furthermore, the connections among two or more sets of entities are called relationships. The idea of a key on a table is central to the relational model. The purpose of a key is to identify each row uniquely. A primary key is the attribute (or combination of attributes) that uniquely identifies one row or record. On the other hand, a foreign key is the attribute (or combination of attributes) that appears as a primary key in another table. Foreign key relationships provide the basis for establishing relationships across tables in a relational database.
Databases
Published in Ian Foster, Rayid Ghani, Ron S. Jarmin, Frauke Kreuter, Julia Lane, Big Data and Social Science, 2020
A related concept is that a column or list of columns may be declared primary key or unique. Such a statement specifies that no two tuples of the table may agree in the specified column—or, if a list of columns is provided, in all of those columns. There can be only one primary key for a table, but several unique columns. No column of a primary key can ever be null in any tuple. But, columns declared unique may have nulls, and there may be several tuples with null.
Introduction to the SAS- and R-Based Table-Driven Environment
Published in Tanya Kolosova, Samuel Berestizhevsky, Supervised Machine Learning, 2020
Tanya Kolosova, Samuel Berestizhevsky
According to the relational data model, every table must have a primary key. A primary key is a column, or set of columns, that makes each row of the table unique. Any column (or columns) can be used as the primary key as long as it defines a unique value for every row in the relational table.
Are NoSQL Databases Affected by Schema?
Published in IETE Journal of Research, 2023
Neha Bansal, Shelly Sachdeva, Lalit K. Awasthi
Column Store (Cassandra) models the 1:1 relationship by creating a single-column family with columns representing the attributes of both entities. To model the 1:1 relation among E1 and E2, create a single-column family with columns representing the attributes of both E1 and E2. 1: N or N:1 relationship is modelled by creating a separate column family for the “many” sides of the relationship and using a partition key corresponding to the “one” side. For taken example in Figure 6, the relationship 1:N and N:1 can be modelled by creating a separate column family for E2 and using a partition key corresponding to the primary key of E1, and creating a separate column family for E1 and using a partition key corresponding to the primary key of E2 respectively. M: N relationship is modelled by creating three-column families, two-column families representing the two entities with the primary key as the partitioning key, and a third-column family with the primary keys of both tables representing the clustering key. For example, create column families E1 and E2 having primary key as partitioning key and third column family E1_E2 having primary keys of both E1 and E2 representing as clustering key.
Traceability and ownership claim of data on big data marketplace using blockchain technology
Published in Journal of Information and Telecommunication, 2021
Given a database relation R(P, , ) where P is the primary key attribute and , are candidate attributes (numeric) used for marking. The embedding and detection of watermarks are depicted in Algorithms 1 and 2 respectively. In Algorithm 1, once a tuple r is found eligible for marking at step 2, the index i of the candidate attribute and its corresponding LSB position j are computed at steps 3 and 4, respectively. Step 5 invokes Mark function which flips the bit at jth LSB position in ith attribute depending on the hash of the private key concatenated with the primary key of the corresponding tuple. Observe that H and F are one-way hash and MAC functions, respectively.
Secure data outsourcing in presence of the inference problem: issues and directions
Published in Journal of Information and Telecommunication, 2021
Adel Jebali, Salma Sassi, Abderrazak Jemai
Authors in Bkakria et al. (2013a) have built on Bkakria et al. (2013b) to propose an approach that securely outsourcing data based on fragmentation and encryption. It also enforces access control when querying data by resorting to query privacy technique. The approach treated the case of multi-relations database and a new inter-table confidentiality constraints was introduced. It assumes that the distributed servers could collude to break data confidentiality so the connection between servers is supposed to be based on primary-key/foreign key. In addition, the query evaluation model which is based on private information retrieval ensure data unlinkability performed by malicious user using semi join query. Even though, the proposed technique enforces database schema to be normalized, and generates a huge number of confidentiality constraints due to the transformation of inter-table constraints to singleton and association constraints which could affect the quality of the fragmentation algorithm. In addition, more generic queries should be considered.