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Re: optional reference

From: Pushpendra Singh Thakur <thakur(at)corexprts(dot)com>
To: pgsql-novice(at)postgresql(dot)org
Cc: wchouse(at)bellsouth(dot)net
Subject: Re: optional reference
Date: 2010-01-24 10:00:53
Message-ID: d6a413081001240200p34710c25w30683c53fbf14049@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-novice
create a third table to store your relations only.
Relation table C
create table C(
a_col1 char(8) references a(column_1),
b_col1 char(8) references b(column_1))

Both the tables will be independent (a and b) i mean they will not have any
direct relations.

2010/1/24 bill house <wchouse(at)bellsouth(dot)net>

> Hello,
>
> What is a technique to reference some (but not all) rows from table a to a
> row in table b?
>
> For example:
>
> ---------------------------
>
> DROP TABLE a;
> DROP TABLE b;
>
>
> CREATE TABLE a (
>  column_1 character(8),
>  column_2 character(2),
>  column_3 character(40)
>  );
>
> INSERT INTO a VALUES
>  ('20901234', '01', 'This is a the first row'),
>  ('20901234', '01', 'This is the second row'),
>  ('20901234', '01', 'This is the third row'),
>  ('20901235', '01', 'This is the fourth row'),
>  ('20901236', '01', 'This is the fifth row'),
>  ('20901236', '01', 'This is the sixth row'),
>  ('20901237', '01', 'This is the seventh row'),
>  ('20901238', '01', 'This is the eighth row');
>
> CREATE TABLE b (
>  column_1 character(8),
>  column_2 character(2),
>  column_3 character(40),
>  PRIMARY KEY (column_1, column_2)
>  );
>
>  INSERT INTO b VALUES
>  ('20901234', '01', 'Footnote #1'),
>  ('20901234', '02', 'other stuff'),
>  ('20901237', '01', 'Footnote #2');
>
> --------------------------------------
>
> Table a rows 1, 2 & 3 should point to table b row 1.
>
> Table a row 7 should point to table b row 3.
>
> Any guidance would be appreciated.
>
> Thanks,
>
> Bill House
>
>
>
>
> --
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-- 
Pushpendra Singh Thakur

COREEXPERTS Technologies Private Limited
Business Process Automation & IT Support Services
http://www.corexprts.com
Phone - 91-761-4070036
Fax - 91-761-4010530
SMS - 91-799-66554

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