Databases and Systems

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journal: VRT : { uncontrolled: string,
controlled: VRT { medline-jta: string,
\* Medline journal title abbrev.\*
iso-jta:string,
\*ISO journal title abbreviation\*
journal-title: string,
volume: string,
issue: string,
year: int,
pages: string,
abstract: string,
keywd: SET{string}} }
In general, the types are given by the syntax:
:=int|bool|string|...|
\* Full journal title\*
issn: string }}
\ *ISSN number\ *
Here bool|int | string|... are the (built-in) base types. The other types are all
constructors and build new types from existing types. RCD{l
constructs record types from the types VRT{l
constructs variant types from the types .. . , and
respectively construct set, bag, and list types from the type .
Values of these types can be explicitly constructed in CPL as follows:
RCD{l 1:e 1,l 2:e 2 ,..., l n:e n} for records; VRT{l : e } for variants, SET{e 1,...,e n} for
sets; and similarly for bags and lists. For example, a fragment of data conforming to
the Publication type is
SET{ RCD{title : “Structure of the human perforin gene",
authors : LIST{RCD{ name : “Lichtenheld",
initial : “MG"},
RCD{name : “Podack",
initial : “ER"}},
journal: VRT{controlled: VRT{medline-jta:”J Immunol”}}
volume:”143",
issue:”12",
year:1989,