RE: Select by priority - Mailing list pgsql-sql

>>  I think the order thing will work though I have no choice of using
>>  numbering for the address_type as I am working off a pre-existing
>>  database. They are using a mnemonic char type. I am essentially batch
>>  downloading and processing this and other database tables for query
>>  and presentations using web pages. BTW, does the 'limit' feature exist
>>  in Oracle? The main database I am extracting data from is Oracle...

I do not know whether you can add a table associating "priority" with
"address_type".  If you can, you might try something like the following
example, using the address_priority table:
   create table address_table (     person_id    integer,     address_type varchar(1),     address      varchar(50)
);
   insert into address_table values ( 1, 'W', 'ROUTE 1, WORK ST');
   insert into address_table values ( 2, 'H', 'ROUTE 2, HOME AVE');
   insert into address_table values ( 3, 'W', 'ROUTE 3, WORK ST');   insert into address_table values ( 3, 'H', 'ROUTE
3,HOME AVE');
 
   insert into address_table values ( 4, 'M', 'ROUTE 4, MAIL RD');
   insert into address_table values ( 5, 'M', 'ROUTE 5, MAIL RD');   insert into address_table values ( 5, 'W', 'ROUTE
5,WORK ST');
 
   insert into address_table values ( 6, 'M', 'ROUTE 6, MAIL RD');   insert into address_table values ( 6, 'H', 'ROUTE
6,HOME AVE');
 
   insert into address_table values ( 7, 'M', 'ROUTE 7, MAIL RD');   insert into address_table values ( 7, 'H', 'ROUTE
7,HOME AVE');   insert into address_table values ( 7, 'W', 'ROUTE 7, WORK ST');
 
   create table address_priority (     address_type varchar(1),      priority     integer   );
   insert into address_priority values ( 'M', 1 );   insert into address_priority values ( 'H', 2 );   insert into
address_priorityvalues ( 'W', 3 );
 
   select person_id, address   from address_table a, address_priority b   where     (person_id, priority) in
(selectperson_id, min(priority)        from address_table a, address_priority b         where a.address_type =
b.address_type       group by person_id) and     a.address_type = b.address_type;
 
    PERSON_ID ADDRESS   ---------- --------------------------------------------------            1 ROUTE 1, WORK ST
      2 ROUTE 2, HOME AVE            3 ROUTE 3, HOME AVE            4 ROUTE 4, MAIL RD            5 ROUTE 5, MAIL RD
       6 ROUTE 6, MAIL RD            7 ROUTE 7, MAIL RD
 

Appears to work with either Oracle or Postgres (though I changed VARCHAR
to VARCHAR2 for Oracle).

Gary Farmer