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From: Carolin Engel <engel@freia.inf.tu-dresden.de>
Subject: question
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To: postgres@postgres.berkeley.edu
Date: Tue, 16 Jun 92 13:27:02 MESZ
Mailer: Elm [revision: 64.9]


Dresden, 15.06.1992

Dear Sirs !

I'm a graduate student at the Technical University Dresden in the
department of databases.
I'm dealing with Yours system POSTGRES, Version 3.0 but I have
some problems:

1. I have defined your example object class "emp":
     emp (name = char16, ..., budget = int4[12]) \g
   (found in the Reference Manual, 1/16/90, Page 18)
   I want to access the first element of vector "budget" addressing
   it with the angular brackets:
     replace emp (budget[1] = 10) \g
   But it come an error message : Syntax error at or near "["
  
   How can I address the i-th element of a vector ?

2. I have defined the following object classes and type:
     create ADDRESS(city = char16, street = char16) \g
     define type T_ADDR (internallength = -1,
                       input = array_in,
                       output = array_out,
                       element = ADDRESS) \g
     create PERSON (name = char16, age = int2, adr = T_ADDR[]) \g
     

   I want to append data to the object class PERSON so that a
   person can have many different addresses.
   That give a problem because the possibility define an attribute
   as a postquel function described in the article "The POSTGRES
   Data Model" (Page 11)
   (for example: create PERSON (name = char16, adr = postquel)\g)
   and than append data in the form
     append PERSON (name ="Charles", adr ="retrieve (A.all)
                    from A in address where A.city ="Dresden")\g
   is not allowed in Version 3.0.
   The execute-command doesn't work too.

   My question: How can I append values to an object class as
   subobject references from another object class using my class
   and type definition described over?

3. Can You send me some more information about handling Large
   Objects (Large Object Backend Interface)?


Gratefull for Your help !

Carolin Engel


My e-mail-address:
x-400 :   engel@serv1.informatik.tu-dresden.dbp.de
or UNIX:  engel@freia.inf.tu-dresden.de