Обсуждение: two questions

I am having two questions about psql:

1. How to define a relation with an attribute which takes set values?
    Not really sure what you mean....

  eg. I would like to define a table like
       create table emp (name  text, tele  Set(string));  -- it does
               not work
       One tuple may look like 'Jerry', {83023381,83023800}
       I can not use array since an array is not a set.

2. How to populate instances to a table referring another table? An
   example:
    Create table CITIES (name  text, population  float);
    Insert into cities values ('Adelaide', 100.0);
    Create table people(name  text, live_in  CITIES);
    How to insert a tuple into people saying that 'Jerry' lives in
            Adelaide?
    I can not use
          INSERT INTO people('Jerry', 'Adelaide');
          since  live_in is not a string, it is a table named CITIES
    I am trying to use object reference of OR. Thus a reference path
        can be formed.

Jerry Liu, Australia

> I am having two questions about psql:
>
> 1. How to define a relation with an attribute which takes set values?
>     Not really sure what you mean....
>
>   eg. I would like to define a table like
>        create table emp (name  text, tele  Set(string));  -- it does
>                not work
>        One tuple may look like 'Jerry', {83023381,83023800}
>        I can not use array since an array is not a set.
>
> 2. How to populate instances to a table referring another table? An
>    example:
>     Create table CITIES (name  text, population  float);
>     Insert into cities values ('Adelaide', 100.0);
>     Create table people(name  text, live_in  CITIES);
>     How to insert a tuple into people saying that 'Jerry' lives in
>             Adelaide?
>     I can not use
>           INSERT INTO people('Jerry', 'Adelaide');
>           since  live_in is not a string, it is a table named CITIES
>     I am trying to use object reference of OR. Thus a reference path
>         can be formed.
>
> Jerry Liu, Australia

The usual approach is to use two tables.

create table cities (name text, population float);
create table people (name text, city_name text);
insert into cities values ('Adelaide', 100.0);
insert into people values ('Jerry', 'Adelaide');
update cities set population = population + 1 where name = 'Adelaide';

I miss <subject>. I know the answer is that I can write them myself,
but I don't know where to start or end.

See this construct:
CREATE TABLE gl-amount (
    glam_nr int,
    period date,
    entry_amount numeric(9,0),
    PRIMARY KEY (glam_seq,period)
    );

CREATE VIEW glam_curmth_v AS
    SELECT entry_amount AS amount1 FROM gl-amount
    WHERE date_part(year', period) = date_part('year', now::datetime)
    AND date_part('month', period) = 1
    UNION SELECT entry_amount AS amount2 FROM gl-amount
    WHERE type = 'S' AND  period = 2;

   SELECT entry_amount AS amount1 FROM gl-amount
    WHERE date_part('year', period) = date_part('year', 'now'::datetime)
    AND date_part('month', period) = 1
    UNION SELECT entry_amount AS amount2 FROM gl-amount
    WHERE date_part('year', period) = date_part('year', 'now'::datetime)
    AND date_part('month', period) = 2
    ...

Can it be done without the use of VIEW's on UNION's?