The discrepancy is that Halpin's use of the phrase relates to the correspondence between the real world and the database - to the modelling relationship itself, whereas Meijer and Bierman's use solely relates to the valid states of the database - separate from any meaning that might be taken.
You highlighted the element of referential integrity within their description, whereas I highlighted atomicity. But both are just operational characteristics of the database.
Halpin's CWA comes into play even within a database that is not being updated and has only one relation. Eg. Consider a relation P that models the fact type that person with NAME was born on DOB.
P = { {NAME: Bob, DOB: 2/2/22} }
CWA answers the query "Was Mary born on 2/2/22?" with False.
Comments
The discrepancy is that Halpin's use of the phrase relates to the correspondence between the real world and the database - to the modelling relationship itself, whereas Meijer and Bierman's use solely relates to the valid states of the database - separate from any meaning that might be taken.
You highlighted the element of referential integrity within their description, whereas I highlighted atomicity. But both are just operational characteristics of the database.
Halpin's CWA comes into play even within a database that is not being updated and has only one relation. Eg. Consider a relation P that models the fact type that person with NAME was born on DOB. P = { {NAME: Bob, DOB: 2/2/22} }
CWA answers the query "Was Mary born on 2/2/22?" with False.