Hi
I would like to know if anyone could answer my questions:
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Structured Types
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1) What collection types does PostgreSQL support, i.e. lists, arrays, setof
and bagof?
As far as I can see it supports arrays and multidimensional arrays. It also
supports setof(type) as a return type in a function.
e.g.
CREATE TABLE Class (CourseId char(7), Year char(2), Students text[]);
However below does not work with setof(text):
CREATE TABLE Class_Nest(CourseID char(7), Year char(2), Students setof(text));
2) How to iterate through the collection type? Which is I presume is just
arrays.
I can currently only access one element at a time in the array but would like
to know how to iterate through an array?
3) What set oriented operations ( i.e. IN, SUBSET, UNION, INTERSECT,
EXCEPT...) are allowed on the collection types (i.e. lists, arrays, setof and
bagof)?
I can't get anyone them to work on a collection type of an array.
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Oids and Reference Types
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1) Does PostgreSQL support tuple AND table oids? I believe tuple oids are like
unique ids for each row in a table/relation. However I am confused over what
a table oid is. Is a table oid an identifier for a complete table/relation?
e.g. if there were three tables A,B, and C then we could assign 3 different
oids to them say 1,2, and 3 respectively.
2) Can you dereference tuples or columns in a query by using a "deref"
function (DEREF is a keyword) for '.' or C type syntax '->'. i.e
select e.Job->jobid
from Employee e;
or
select e.deref(Job).jobid
from Employee e;
I can't seem to get either option to work.
Cheers Craig
Email: craig@mcs.vuw.ac.nz
