Thread: CONCAT returns null

CONCAT returns null

From

"Sterpu Victor"

Date:

28 February 2016, 13:03:05

Hello

I have this concat:

CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))

that works fine but when I change to this(I added a ' with '):

ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' with ', f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))) AS temp,

then concat returns NULL.

Why? I tried to add ' with '::VARCHAR and ' with '::TEXT but the result is still NULL.

Thank you

This is part of a bigger query that I wrote down.

SELECT d1.id AS id, d1.name AS name, COUNT(DISTINCT(f2.id)) AS nr_spitalizari,
ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' cu ', f2.nrfo, '/', TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), ' diferenta de ', DATE(fd5.validto)-DATE(fd1.validfrom), ' zile ')) AS fise

FROM focg f
JOIN person p ON p.id = f.idpatient
JOIN focgdepartment fd1 ON fd1.idfocg = f.id
JOIN department d1 ON d1.id = fd1.iddepartment
LEFT JOIN focgdepartment fd2 ON fd2.idfocg = f.id AND fd2.validfrom < fd1.validfrom
JOIN focgdepartment fd3 ON fd3.idfocg = f.id
JOIN department d2 ON d2.id = fd3.iddepartment
LEFT JOIN focgdepartment fd4 ON fd4.idfocg = f.id AND fd4.validfrom > fd3.validfrom

JOIN focg f2 ON f2.idpatient = f.idpatient AND f2.id != f.id
JOIN focgdepartment fd5 ON fd5.idfocg = f2.id
LEFT JOIN focgdepartment fd6 ON fd6.idfocg = f2.id AND fd6.validfrom > fd5.validfrom
JOIN focgdepartment fd7 ON fd7.idfocg = f2.id
LEFT JOIN focgdepartment fd8 ON fd8.idfocg = f2.id AND fd8.validfrom < fd8.validfrom

WHERE fd2.id IS NULL AND fd4.id IS NULL AND fd6.id IS NULL AND fd8.id IS NULL AND fd5.validto IS NOT NULL AND fd1.validfrom >= '2015-02-01' AND fd1.validfrom <= '2016-02-29' AND DATE(fd5.validto)-DATE(fd1.validfrom)<=30 AND DATE(fd5.validto)-DATE(fd1.validfrom)>=0
GROUP BY d1.name, d1.id;

DISCLAIMER:
Acest mesaj de posta electronica si documentele aferente sunt confidentiale. Este interzisa distribuirea, dezvaluirea sau orice alt mod de utilizare a lor. Daca nu sunteti destinatarul acestui mesaj, este interzis sa actionati in baza acestor informatii. Citirea, copierea, distribuirea, dezvaluirea sau utilizarea in alt mod a informatiei continute in acest mesaj constituie o incalcare a legii. Daca ati primit mesajul din greseala, va rugam sa il distrugeti, anuntand expeditorul de eroarea comisa. Intrucat nu poate fi garantat faptul ca posta electronica este un mod sigur si lipsit de erori de transmitere a informatiilor, este responsabilitatea dvs. sa va asigurati ca mesajul (inclusiv documentele alaturate lui) este validat si autorizat spre a fi utilizat in mediul dvs.

Re: CONCAT returns null

From

"Charles Clavadetscher"

Date:

28 February 2016, 13:24:35

Hello

Just a short question to that.

> CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'),
> DATE(fd5.validto)-DATE(fd1.validfrom))
> that works fine but when I change to this(I added a ' with '):
> ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' with ', f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-
> MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))) AS temp,
> then concat returns NULL.
> Why? I tried to add ' with '::VARCHAR and ' with '::TEXT but the result is still NULL.

Do you get NULL also if you run the query without the call to array_agg(), i.e. for all entries in your table?

Bye
Charles

Re: CONCAT returns null

From

Andreas Kretschmer

Date:

28 February 2016, 13:30:25

Sterpu Victor <victor@caido.ro> wrote:

> Hello
>
> I have this concat:
> CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), f2.nrfo, TO_CHAR
> (fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))
> that works fine but when I change to this(I added a ' with '):
> ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' with ',
> f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE
> (fd1.validfrom))) AS temp,
> then concat returns NULL.
> Why? I tried to add ' with '::VARCHAR and ' with '::TEXT but the result is
> still NULL.
>
> Thank you

NULL concat with a value returns NULL. You can avoid that using
COALESCE(value, ''), that returns the value, or, if the value NULL, ''.


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°

Re: CONCAT returns null

From

"Charles Clavadetscher"

Date:

28 February 2016, 13:30:27

Hello again

> -----Original Message-----
> From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Charles
> Clavadetscher
> Sent: Sonntag, 28. Februar 2016 11:24
> To: 'Sterpu Victor' <victor@caido.ro>; 'PostgreSQL General' <pgsql-general@postgresql.org>
> Subject: Re: [GENERAL] CONCAT returns null
>
> Hello
>
> Just a short question to that.
>
> > CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'),
> > DATE(fd5.validto)-DATE(fd1.validfrom))
> > that works fine but when I change to this(I added a ' with '):
> > ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' with ', f2.nrfo, TO_CHAR(fd7.validfrom,
> 'YYYY-
> > MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))) AS temp,
> > then concat returns NULL.
> > Why? I tried to add ' with '::VARCHAR and ' with '::TEXT but the result is still NULL.
>
> Do you get NULL also if you run the query without the call to array_agg(), i.e. for all entries in your table?

Forget it. Should not depend on that. If you have any null entry it will be added in the array as NULL.
Bye
Charles

Re: CONCAT returns null

From

"Charles Clavadetscher"

Date:

28 February 2016, 13:44:24

Hello

> -----Original Message-----
> From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Andreas Kretschmer
> Sent: Sonntag, 28. Februar 2016 11:30
> To: pgsql-general@postgresql.org
> Subject: Re: [GENERAL] CONCAT returns null
>
> Sterpu Victor <victor@caido.ro> wrote:
>
> > Hello
> >
> > I have this concat:
> > CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), f2.nrfo, TO_CHAR
> > (fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))
> > that works fine but when I change to this(I added a ' with '):
> > ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' with ',
> > f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE
> > (fd1.validfrom))) AS temp,
> > then concat returns NULL.
> > Why? I tried to add ' with '::VARCHAR and ' with '::TEXT but the result is
> > still NULL.
> >
> > Thank you
>
> NULL concat with a value returns NULL. You can avoid that using
> COALESCE(value, ''), that returns the value, or, if the value NULL, ''.

That was my first thought, too, but:

db=> select concat(null,'sssdf',null,'dfg',NULL);
  concat
----------
 sssdfdfg
(1 row)

Bye Charles

Re: CONCAT returns null

From

"Sterpu Victor"

Date:

28 February 2016, 15:56:58

The problem was from PG Admin that is not displaing cells with a high amount of data.

In the application the query is working well.

------ Original Message ------

From: "Sterpu Victor" <victor@caido.ro>

To: "PostgreSQL General" <pgsql-general@postgresql.org>

Sent: 28/2/2016 12:02:47 PM

Subject: [GENERAL] CONCAT returns null

Hello

I have this concat:
CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))
that works fine but when I change to this(I added a ' with '):
ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' with ', f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))) AS temp,
then concat returns NULL.
Why? I tried to add ' with '::VARCHAR and ' with '::TEXT but the result is still NULL.

Thank you

This is part of a bigger query that I wrote down.
SELECT d1.id AS id, d1.name AS name, COUNT(DISTINCT(f2.id)) AS nr_spitalizari,
ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' cu ', f2.nrfo, '/', TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), ' diferenta de ', DATE(fd5.validto)-DATE(fd1.validfrom), ' zile ')) AS fise

FROM focg f
JOIN person p ON p.id = f.idpatient
JOIN focgdepartment fd1 ON fd1.idfocg = f.id
JOIN department d1 ON d1.id = fd1.iddepartment
LEFT JOIN focgdepartment fd2 ON fd2.idfocg = f.id AND fd2.validfrom < fd1.validfrom
JOIN focgdepartment fd3 ON fd3.idfocg = f.id
JOIN department d2 ON d2.id = fd3.iddepartment
LEFT JOIN focgdepartment fd4 ON fd4.idfocg = f.id AND fd4.validfrom > fd3.validfrom

JOIN focg f2 ON f2.idpatient = f.idpatient AND f2.id != f.id
JOIN focgdepartment fd5 ON fd5.idfocg = f2.id
LEFT JOIN focgdepartment fd6 ON fd6.idfocg = f2.id AND fd6.validfrom > fd5.validfrom
JOIN focgdepartment fd7 ON fd7.idfocg = f2.id
LEFT JOIN focgdepartment fd8 ON fd8.idfocg = f2.id AND fd8.validfrom < fd8.validfrom

WHERE fd2.id IS NULL AND fd4.id IS NULL AND fd6.id IS NULL AND fd8.id IS NULL AND fd5.validto IS NOT NULL AND fd1.validfrom >= '2015-02-01' AND fd1.validfrom <= '2016-02-29' AND DATE(fd5.validto)-DATE(fd1.validfrom)<=30 AND DATE(fd5.validto)-DATE(fd1.validfrom)>=0
GROUP BY d1.name, d1.id;

DISCLAIMER:
Acest mesaj de posta electronica si documentele aferente sunt confidentiale. Este interzisa distribuirea, dezvaluirea sau orice alt mod de utilizare a lor. Daca nu sunteti destinatarul acestui mesaj, este interzis sa actionati in baza acestor informatii. Citirea, copierea, distribuirea, dezvaluirea sau utilizarea in alt mod a informatiei continute in acest mesaj constituie o incalcare a legii. Daca ati primit mesajul din greseala, va rugam sa il distrugeti, anuntand expeditorul de eroarea comisa. Intrucat nu poate fi garantat faptul ca posta electronica este un mod sigur si lipsit de erori de transmitere a informatiilor, este responsabilitatea dvs. sa va asigurati ca mesajul (inclusiv documentele alaturate lui) este validat si autorizat spre a fi utilizat in mediul dvs.

Re: CONCAT returns null

From

Adrian Klaver

Date:

28 February 2016, 19:23:07

On 02/28/2016 02:30 AM, Andreas Kretschmer wrote:
> Sterpu Victor <victor@caido.ro> wrote:
>
>> Hello
>>
>> I have this concat:
>> CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), f2.nrfo, TO_CHAR
>> (fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE(fd1.validfrom))
>> that works fine but when I change to this(I added a ' with '):
>> ARRAY_AGG(CONCAT(f.nrfo, '/', TO_CHAR(fd1.validfrom, 'YYYY-MM-DD'), ' with ',
>> f2.nrfo, TO_CHAR(fd7.validfrom, 'YYYY-MM-DD'), DATE(fd5.validto)-DATE
>> (fd1.validfrom))) AS temp,
>> then concat returns NULL.
>> Why? I tried to add ' with '::VARCHAR and ' with '::TEXT but the result is
>> still NULL.
>>
>> Thank you
>
> NULL concat with a value returns NULL. You can avoid that using
> COALESCE(value, ''), that returns the value, or, if the value NULL, ''.


http://www.postgresql.org/docs/9.5/interactive/functions-string.html
"
concat(str "any" [, str "any" [, ...] ])     text     Concatenate the text
representations of all the arguments. NULL arguments are ignored.
"
>
>
> Andreas
>


--
Adrian Klaver
adrian.klaver@aklaver.com

Re: CONCAT returns null

From

Andreas Kretschmer

Date:

28 February 2016, 19:30:51

Adrian Klaver <adrian.klaver@aklaver.com> wrote:

>>
>> NULL concat with a value returns NULL. You can avoid that using
>> COALESCE(value, ''), that returns the value, or, if the value NULL, ''.
>
>
> http://www.postgresql.org/docs/9.5/interactive/functions-string.html
> "
> concat(str "any" [, str "any" [, ...] ])     text     Concatenate the text
> representations of all the arguments. NULL arguments are ignored.
> "

you are right, my fault :-(, muddled with the || - operator.


Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect.                              (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly."   (unknown)
Kaufbach, Saxony, Germany, Europe.              N 51.05082°, E 13.56889°