Dear all,

given a column which type is for instance varchar(20)[], is there any SQL
command that let me generate the list of distinct scalar values?


e.g.:
col1
row 1: (aaa, bb, c)
row 2: (dddd, eeee)
row 3: (aaa, eeee)

the query should return:

aaa
bb
c
dddd
eeee

if not, I guess the approach is to use stored procedure. Any code
snippet/suggestion?

Thanks, Sergio

am Wed, dem 21.02.2007, um 19:21:09 +0100 mailte Sergio Andreozzi folgendes:
> Dear all,
>
> given a column which type is for instance varchar(20)[], is there any SQL
> command that let me generate the list of distinct scalar values?
>
>
> e.g.:
> col1
> row 1: (aaa, bb, c)
> row 2: (dddd, eeee)
> row 3: (aaa, eeee)
>
> the query should return:
>
> aaa
> bb
> c
> dddd
> eeee
>
> if not, I guess the approach is to use stored procedure. Any code snippet/
> suggestion?

You can, for each row, split the array into the elements with a loop
over array_lower, array_upper, returns this element. Yes, this is a
setof-function. Than you can do a simple select distinct * from
your_function.


I hope this may help you.


Andreas
--
Andreas Kretschmer
Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
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am Wed, dem 21.02.2007, um 19:21:09 +0100 mailte Sergio Andreozzi folgendes:
> Dear all,
>
> given a column which type is for instance varchar(20)[], is there any SQL
> command that let me generate the list of distinct scalar values?
>
>
> e.g.:
> col1
> row 1: (aaa, bb, c)
> row 2: (dddd, eeee)
> row 3: (aaa, eeee)
>
> the query should return:
>
> aaa
> bb
> c
> dddd
> eeee

Okay, next solution:

test=*# select * from a;
c
-------------
{aaa,bb,c}
{dddd,eeee}
{aaa,eeee}
(3 rows)


test=*# select distinct c[s] from a, generate_series(1,3)s where c[s] is not null;
c
------
aaa
bb
c
dddd
eeee
(5 rows)


You need to know the greatest upper dimension of the array, in this case
3, for the generate_series - function.


Andreas
--
Andreas Kretschmer
Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match

am Thu, dem 22.02.2007, um 14:25:36 +0100 mailte A. Kretschmer folgendes:
> test=*# select * from a;
> c
> -------------
> {aaa,bb,c}
> {dddd,eeee}
> {aaa,eeee}
> (3 rows)
>
>
> test=*# select distinct c[s] from a, generate_series(1,3)s where c[s] is not null;
> c
> ------
> aaa
> bb
> c
> dddd
> eeee
> (5 rows)
>
>
> You need to know the greatest upper dimension of the array, in this case
> 3, for the generate_series - function.

select distinct c[s] from a, generate_series(1,(select max(array_upper(c,1)) from a))s where c[s] is not null;

;-)


Andreas
--
Andreas Kretschmer
Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match