Re: optional reference

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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