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Thread: NULL concatenation

NULL concatenation

From
Sridhar N Bamandlapally
Date:
Hi

In migration, am facing issue with NULL concatenation in plpgsql, 
by concatenating NULL between any where/position to Text / Varchar, the total string result is setting value to NULL


In Oracle:

declare
    txt1 VARCHAR2(100) := 'ABCD';
    txt2 VARCHAR2(100) := NULL;
    txt3 VARCHAR2(100) := 'EFGH';
    txt VARCHAR2(100) := NULL;
begin
  txt:= txt1 || txt2 || txt3;
  dbms_output.put_line (txt);
end;
/

abcdefgh   ===>return value



In Postgres

do $$
declare
    txt1 text := 'ABCD';
    txt2 text := NULL;
    txt3 text := 'EFGH';
    txt text := NULL;
begin
    txt:= txt1 || txt2 || txt3;
    raise notice '%', txt;
end$$ language plpgsql;

NOTICE:  <NULL>  ===> return value


SQL-Server also does same like Oracle

Is there any way alternate we have for same behavior in PostgreSQL

Please

Thanks
Sridhar
OpenText

Re: [HACKERS] NULL concatenation

From
Pavel Stehule
Date:
Hi

2016-05-12 10:47 GMT+02:00 Sridhar N Bamandlapally <sridhar.bn1@gmail.com>:
Hi

In migration, am facing issue with NULL concatenation in plpgsql, 
by concatenating NULL between any where/position to Text / Varchar, the total string result is setting value to NULL


In Oracle:

declare
    txt1 VARCHAR2(100) := 'ABCD';
    txt2 VARCHAR2(100) := NULL;
    txt3 VARCHAR2(100) := 'EFGH';
    txt VARCHAR2(100) := NULL;
begin
  txt:= txt1 || txt2 || txt3;
  dbms_output.put_line (txt);
end;
/

abcdefgh   ===>return value



In Postgres

do $$
declare
    txt1 text := 'ABCD';
    txt2 text := NULL;
    txt3 text := 'EFGH';
    txt text := NULL;
begin
    txt:= txt1 || txt2 || txt3;
    raise notice '%', txt;
end$$ language plpgsql;

NOTICE:  <NULL>  ===> return value


SQL-Server also does same like Oracle

Is there any way alternate we have for same behavior in PostgreSQL

use function concat http://www.postgresql.org/docs/9.5/static/functions-string.html

 postgres=# select concat('AHOJ', NULL,'XXX');
 concat 
---------
 AHOJXXX
(1 row)

Regards

Pavel


Please

Thanks
Sridhar
OpenText


Re: NULL concatenation

From
Tim Clarke
Date:
Wrap the source columns in your line:

txt:= txt1 || txt2 || txt3;

 in coalesce() calls

Tim Clarke

On 12/05/16 09:47, Sridhar N Bamandlapally wrote:
> txt:= txt1 || txt2 || txt3;
Attachment

Re: [HACKERS] NULL concatenation

From
Sridhar N Bamandlapally
Date:
Thanks Pavel

Great !!

I was thinking both || and CANCAT does same

Thanks again

-
Sridhar
OpenText


On Thu, May 12, 2016 at 2:22 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
Hi

2016-05-12 10:47 GMT+02:00 Sridhar N Bamandlapally <sridhar.bn1@gmail.com>:
Hi

In migration, am facing issue with NULL concatenation in plpgsql, 
by concatenating NULL between any where/position to Text / Varchar, the total string result is setting value to NULL


In Oracle:

declare
    txt1 VARCHAR2(100) := 'ABCD';
    txt2 VARCHAR2(100) := NULL;
    txt3 VARCHAR2(100) := 'EFGH';
    txt VARCHAR2(100) := NULL;
begin
  txt:= txt1 || txt2 || txt3;
  dbms_output.put_line (txt);
end;
/

abcdefgh   ===>return value



In Postgres

do $$
declare
    txt1 text := 'ABCD';
    txt2 text := NULL;
    txt3 text := 'EFGH';
    txt text := NULL;
begin
    txt:= txt1 || txt2 || txt3;
    raise notice '%', txt;
end$$ language plpgsql;

NOTICE:  <NULL>  ===> return value


SQL-Server also does same like Oracle

Is there any way alternate we have for same behavior in PostgreSQL

use function concat http://www.postgresql.org/docs/9.5/static/functions-string.html

 postgres=# select concat('AHOJ', NULL,'XXX');
 concat 
---------
 AHOJXXX
(1 row)

Regards

Pavel


Please

Thanks
Sridhar
OpenText



Re: NULL concatenation

From
Adam Pearson
Date:

Hello Sridhar,

  Have you tried the 'coalesce' function to handle the nulls?


Kind Regards,

Adam Pearson

From: pgsql-general-owner@postgresql.org <pgsql-general-owner@postgresql.org> on behalf of Sridhar N Bamandlapally <sridhar.bn1@gmail.com>
Sent: 12 May 2016 09:47
To: PG-General Mailing List; PostgreSQL-hackers
Subject: [GENERAL] NULL concatenation
 
Hi

In migration, am facing issue with NULL concatenation in plpgsql, 
by concatenating NULL between any where/position to Text / Varchar, the total string result is setting value to NULL


In Oracle:

declare
    txt1 VARCHAR2(100) := 'ABCD';
    txt2 VARCHAR2(100) := NULL;
    txt3 VARCHAR2(100) := 'EFGH';
    txt VARCHAR2(100) := NULL;
begin
  txt:= txt1 || txt2 || txt3;
  dbms_output.put_line (txt);
end;
/

abcdefgh   ===>return value



In Postgres

do $$
declare
    txt1 text := 'ABCD';
    txt2 text := NULL;
    txt3 text := 'EFGH';
    txt text := NULL;
begin
    txt:= txt1 || txt2 || txt3;
    raise notice '%', txt;
end$$ language plpgsql;

NOTICE:  <NULL>  ===> return value


SQL-Server also does same like Oracle

Is there any way alternate we have for same behavior in PostgreSQL

Please

Thanks
Sridhar
OpenText

Re: NULL concatenation

From
Sridhar N Bamandlapally
Date:
Hi Adam

we need simple concatenation of all variables(which values may come NULL or valid-values based on functional process), 

coalesce is different functionality

Thanks
Sridhar
OpenText
  

On Thu, May 12, 2016 at 4:56 PM, Adam Pearson <adam.pearson@realisticgames.co.uk> wrote:

Hello Sridhar,

  Have you tried the 'coalesce' function to handle the nulls?


Kind Regards,

Adam Pearson

From: pgsql-general-owner@postgresql.org <pgsql-general-owner@postgresql.org> on behalf of Sridhar N Bamandlapally <sridhar.bn1@gmail.com>
Sent: 12 May 2016 09:47
To: PG-General Mailing List; PostgreSQL-hackers
Subject: [GENERAL] NULL concatenation
 
Hi

In migration, am facing issue with NULL concatenation in plpgsql, 
by concatenating NULL between any where/position to Text / Varchar, the total string result is setting value to NULL


In Oracle:

declare
    txt1 VARCHAR2(100) := 'ABCD';
    txt2 VARCHAR2(100) := NULL;
    txt3 VARCHAR2(100) := 'EFGH';
    txt VARCHAR2(100) := NULL;
begin
  txt:= txt1 || txt2 || txt3;
  dbms_output.put_line (txt);
end;
/

abcdefgh   ===>return value



In Postgres

do $$
declare
    txt1 text := 'ABCD';
    txt2 text := NULL;
    txt3 text := 'EFGH';
    txt text := NULL;
begin
    txt:= txt1 || txt2 || txt3;
    raise notice '%', txt;
end$$ language plpgsql;

NOTICE:  <NULL>  ===> return value


SQL-Server also does same like Oracle

Is there any way alternate we have for same behavior in PostgreSQL

Please

Thanks
Sridhar
OpenText


Re: NULL concatenation

From
George Neuner
Date:
On Fri, 13 May 2016 08:45:46 +0530, Sridhar N Bamandlapally
<sridhar.bn1@gmail.com> wrote:

>we need simple concatenation of all variables(which values may come NULL or
>valid-values based on functional process),
>
>coalesce is different functionality

As Pavel suggested, concat will work, but it swallows NULLs leaving no
trace of them in the output.  Using coalesce *with* concat lets you
decide what a NULL will look like:

e.g.,

>> do $$
>> declare
>>     txt1 text := 'ABCD';
>>     txt2 text := NULL;
>>     txt3 text := 'EFGH';
>>     txt text := NULL;
>> begin

  txt := coalesce( txt1, '' )
        || coalesce( txt2, 'txt2 was null' )
        || coalesce( txt3, '<null>') ;

>>     raise notice '%', txt;
>> end$$ language plpgsql;

George