"Entity-Relationship Model"

“One of the first formal attempts at a framework for Data Modeling was the Entity-Relationship data model paradigm proposed [in 1976] by Peter Chen. Notice that in the original Chen-style, the attributes are somewhat independent and the relationships between entities are named and carry cardinalities ("how many" participants in each end of the relationship) ... Attributes are related to their "owner" entity" in what other people called "functional dependencies".”

“... I needed to know what the constituent parts of data models really are. Across the board, all platforms, all models etc. Is there anything similar to atoms and the (chemical) bonds that enables the formation of molecules? My concerns were twofold ... I wanted a simple, DIY-style, metadata repository for storing 3-level data models -- what would the meta model of such a thing look like? -- [where] atomicity is of essence ... I took a tour (again) in the Data Modeling zone, trying to deconstruct the absolutely essential metadata, which data modelers cannot do without.”
--Thomas Friesendal, The Atoms and Molecules of Data Models, Dataversity.com

“The relational databases that emerged in the ’80s are efficient at storing and analyzing tabular data but their underlying data model makes it difficult to connect data scattered across multiple tables. The graph databases we’ve seen emerge in the recent years are designed for this purpose. Their data model is particularly well-suited to store and to organize data where connections are as important as individual data points. Connections are stored and indexed as first-class citizens, making it an interesting model for investigations in which you need to connect the dots. In this post, we review three common fraud schemes and see how a graph approach can help investigators defeat them.”

--AnalyticBridge.DataScienceCentral.com

• There is no "tabular data" (the relational data structure is the relation, which can be visualized as a table on a physical medium[2], and SQL tables are not relations);

• Analysis is not a DBMS, but an application function (while database queries, as deductions, are an important aspect of analysis, and computational functions can be added to the data sublanguage (as in SQL), the primary function of a DBMS is data management)[3];

• A data model has nothing to do with storage (storage and access methods are part of physical implementation, which determines efficiency/performance[4]).

“We have Building, Room, and Bed entities. Logically, if this is in the scope of some hypothetical hotel, then each one of those entities is dependent on their parent to exist ... you cannot have a bed without a room. Also, that room wouldn't exist without its parent, Building. So, why have I rarely seen this identifying relationship introduced? When I was learning databases, everything was apparently "non-identifying". When is this type of relationship necessary, if at all? I see the issue arises when that BED can exist without a BUILDING. If you were to INSERT into the BED table, you are constraint [sic] to provide a building_id, as the building_id is part of that BED's primary key. Couldn't you avoid an identifying relationship by giving each table its own surrogate primary key? Is this the correct representation  of an identifying relationship? I could avoid that by just giving each table its own ID. At the end of the day, this is about IDENTIFYING relationships, not their existence, which is how I've been logically determining if something is an "identifying relationship" If that were the case, then any 1:N relationship could be "identifying" but that's not how you define identifying or non-identifying.”

“Interesting -- I’d never heard this term before. I’ve heard it referred to as a cached ID though, as that 2nd ID isn’t required, but may be beneficial for performance purposes. For this example with 3 levels it’s not a huge joint statement, but for some systems with 12 tables the joins get unpleasant. I’ve never started a system with this additional id, but I have added one later on once the need was there and the profiling led to this being the best solution for our specific situation. Usually though, just creating a view that does the joins for me has been easier. I’ll be curious what has led others to use this approach.”

It's not really introduced because it's way more towards academic than functional.”

--Reddit.com

 “We have Building, Room, and Bed entities. Logically, if this is in the scope of some hypothetical hotel, then each one of those entities is dependent on their parent to exist ... you cannot have a bed without a room. Also, that room wouldn't exist without its parent, Building. So, why have I rarely seen this identifying relationship introduced? When I was learning databases, everything was apparently "non-identifying". When is this type of relationship necessary, if at all? I see the issue arises when that BED can exist without a BUILDING. If you were to INSERT into the BED table, you are constraint [sic] to provide a building_id, as the building_id is part of that BED's primary key. Couldn't you avoid an identifying relationship by giving each table its own surrogate primary key? Is this the correct representation  of an identifying relationship? I could avoid that by just giving each table its own ID. At the end of the day, this is about IDENTIFYING relationships, not their existence, which is how I've been logically determining if something is an "identifying relationship" If that were the case, then any 1:N relationship could be "identifying" but that's not how you define identifying or non-identifying.”

“Interesting -- I’d never heard this term before. I’ve hears it referred to as a cached ID though, as that 2nd ID isn’t required, but may be beneficial for performance purposes. For this example with 3 levels it’s not a huge joint statement, but for some systems with 12 tables the joins get unpleasant. I’ve never started a system with this additional id, but I have added one later on once the need was there and the profiling led to this being the best solution for our specific situation. Usually though, just creating a view that does the joins for me has been easier. I’ll be curious what has led others to use this approach.”

“It's not really introduced because it's way more towards academic than functional.”

--Reddit.com

“[According to Date] relvar ≠ class. [But i]n simple terms, class applies to a collection of values allowed by a predicate, regardless of whether such a collection could actually exist. Every set has a corresponding class, although a class may have no corresponding set ... in mathematical logic, a relation is a class (and trivially also a set), which contributes to confusion.”

“In modern programming parlance, class is generally distinguished from type only in that the latter refers to primitive (system-defined) data definitions, while class refers to higher-level (user-defined) data definitions. This distinction is almost arbitrary, and in some contexts, type and class are actually synonymous.”

“I don't understand the concepts of domain and attribute in relational database modeling. Can someone give me an effective example?”

“Domain is an overloaded word in the DB lexicon. It probably should also be avoided. When one refers to an attribute domain in practice it is only referring to columns that have a check constraint on them that limit the values. Reference tables with foreign key constraints in general also fulfill the spirit of what domain attributes do outside of an RDBMS.”

“A domain in most SQL usage is essentially an alias name for an existing type + restrictions on an existing type that can be used in a column. As for an attribute, it's essentially a COLUMN in SQL, a field in other types of databases, etc.”