2 ;;Quote: a mathematical relation is an unordered set of tuples all of the same type

2+;;Quote: mathematical relations as foundation for commercial databases: no numbering, no ordering, no storage addresses, no sense of nextness

2 ;;Quote: each row of a relational table represents a tuple; ordering is immaterial; all rows are distinct

3 ;;Quote: relations are not tables; e.g., they do not allow duplicate rows

3+;;Quote: need discipline of relational model to share large quantities of data by non-programmers acting independently

3 ;;Quote: a database column is a particular use of a domain; named to convey intended meaning without position or nextness

3 ;;Quote: pointers weakly support relations; too complex for casual users; only degree 2, directional, complex data structures

4 ;;Quote: AI researchers write their programs for other AI researchers; incredibly complex data structures

4 ;;Quote: each row of a relation represents an assertion; like a knowledge base; e.g., person A is an employee of the company with these properties

5 ;;Quote: if allow duplicate rows, then all users need to agree on its meaning; no precise, context-independent interpretation

5+;;Quote: the sharing of data requires the sharing of its meaning; a single, simple, explicit description of every row of every relation

7 ;;Quote: entity-relationship describes structure but not operators nor integrity constraints

7+;;Quote: one person's entity is another person's relationship while relations represent both in the same way

12 ;;Quote: SQL was based on the relational model, but it allows duplicate rows and corrupted relations

17 ;;Quote: no "nextness" for rows or columns of a relation; both are position-independent

18 ;;Quote: the primary key plus table name uniquely identifies every row of a relational database; integrity is not enforced by other models

23 ;;Quote: a foreign key refers to a row of another table via a value from the same domain as the primary key

23 ;;Quote: referential integrity if every foreign key refers to a primary key unless marked as a missing values

29 ;;Quote: relational model is for commercial and industrial databases; i.e., a large number of assertions of the same type

29+;;Quote: the database description is like a knowledge base

43 ;;Quote: a domain distinguishes values of the same basic data type with a range and optional ordering

43+;;Quote: domains are the glue that holds a relational database together; shared descriptions; domain integrity, operators, and features

171 ;;Quote: tuples or values may be missing; either applicable, unknown, or inapplicable

171+;;Quote: use A-mark for missing-but-applicable values and I-mark for missing-but-inapplicable values; in place of null values

249 ;;Quote: integrity constraints checked automatically, no voluntary action; concern of the community of users

374 ;;Quote: duplicate rows do not represent distinct objects; a fact is a fact; avoid redundancy

459 ;;Quote: fundamental laws of the relational model apply to all database management systems

459 ;;Quote: the relational model is as powerful as the first-order predicate logic in retrieving information

460 ;;Quote: a database uniquely identifies every object

460 ;;Quote: all users identify database objects in exactly one way, whether abstract, concrete, entities, or relationships

461 ;;Quote: easily split independent sections of a database

461 ;;Quote: explicitly represent and enforce all database issues of concern to the user community; not hidden in applications

461 ;;Quote: both end users and DBMS application programmers should have the same logical level of abstraction

462 ;;Quote: self-contained, logical level of abstraction in a database

462 ;;Quote: the relational model does not need iterative or recursive loops to extract information; few bugs and higher productivity

462 ;;Quote: compare values to interrelate database objects instead of using pointers; well understood by all users

463 ;;Quote: allow online addition and removal of performance-oriented structures for databases; do not stop the database

463 ;;Quote: be careful of over-constraining database types; allow new unforeseen uses; object-orientation is too restrictive

463 ;;Quote: performance-oriented structures should be independent of semantic information in the database and catalog

464 ;;Quote: the results of a database command must be independent of the database organization and access methods

464 ;;Quote: cursors are not required within a database; can lead to severe bugs; e.g., CODASYL

470 ;;Quote: the universal relation misses useful queries that are not based on keys

477 ;;Quote: one person's entity is another's relationship; e.g., an airline flight

477+;;Quote: while relationships typically do not have properties, they may need properties in the future

480 ;;Quote: over time databases expand and some information may be dropped; applications easily adjusted