sql - PostgreSQL conforms to Codds rules? -

sql - PostgreSQL conforms to Codds rules? -

does have references read regarding whether postgresql conforms 12 of codd's rules?

if not, there veteran postgresql users have sentiment on topic?

thank you.

my reply based on other answers via google.

in 1986 created first ansi standard of sql language. lastly ansi standard ansi sql:2003. it's requirements nevertheless implemented in few rdbmss. far widespread rdbmss respect ansi sql:1999, respectively older ansi sql:1992. postgresql supports ansi sql:1999 , partly ansi:2003.

if strictly speaking codd's rules:

codd's 12 rules aren't relational model. in fact, expanded these 12 40 rules in 1.990 book _the_relational_model_for_database_management.

but furthermore, if care read christopher j date's 1.999 _an_introduction_to_database_systems_ see relational model comprises basic elements , principles.

the basic element domain, or info type. postgresql not enforces domains because accepts null, definition not part of domain. triplet domain, name , value called attribute breaks down, , tuple -- because represents proposition, , proposition missing info proposition, not 1 declared in relation's header --, , relation breaks down.

furthermore, relation set, not bag. handbag accepts duplicates, not relation. because postgresql not enforce necessity of declaring candidate key each , every table, tables not relations, quite perchance , commonly bags of not tuples shown above, rows.

also, first principle info principle, database must represented data. object ids violate this, serious consequences info independence, way necessary relational model sine qua non, namely separation between user, logical , physical schemas. not supported postgresql.

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