Обсуждение: SELECT using arrays

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SELECT using arrays

От
Evan Klinger
Дата:
I have been playing around with this for some time now to no avail. I
have a table info with a two-dimensional text type array action. Is
there any way to select the corresponding value of one of the elements
without knowing the order of the elements?

E.g.

CREATE TABLE info (action text[][]);

INSERT INTO info VALUES ('{{"VAR","VAL"},{"VAR2","VAL2"}}');

Now what SELECT query will search for "VAR" within action (in this
case it is the first element, but it may not always be) and print out
"VAL."


Any information would be greatly appreciated.

Thank you very much.

Evan


Re: [SQL] SELECT using arrays

От
Herouth Maoz
Дата:
At 00:05 +0300 on 15/07/1999, Evan Klinger wrote:


> I have been playing around with this for some time now to no avail. I
> have a table info with a two-dimensional text type array action. Is
> there any way to select the corresponding value of one of the elements
> without knowing the order of the elements?
>
> E.g.
>
> CREATE TABLE info (action text[][]);
>
> INSERT INTO info VALUES ('{{"VAR","VAL"},{"VAR2","VAL2"}}');
>
> Now what SELECT query will search for "VAR" within action (in this
> case it is the first element, but it may not always be) and print out
> "VAL."
>
>
> Any information would be greatly appreciated.

I think somewhere, somehow, in the Postgres documentation, it should be
written that arrays are only recommended to be used as a bulk, like a
polygon or an image. You can update them or get a particular item in them,
but nothing furter than that.

If you need anything further, don't use arrays, but use the relational data
model and arrange the related data in a related table. Collecting all the
values together is a pretty easy trick from the frontend. So is population
of the table. The said type of searches should become much much easier.

Herouth

--
Herouth Maoz, Internet developer.
Open University of Israel - Telem project
http://telem.openu.ac.il/~herutma