Re: concatenation issue ( 8.4 )

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От Alban Hertroys
Тема Re: concatenation issue ( 8.4 )
Дата
Msg-id 1B3FB908-2D69-476F-B0D3-2ED7CF852437@solfertje.student.utwente.nl
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Ответ на Re: concatenation issue ( 8.4 )  (Raymond O'Donnell <rod@iol.ie>)
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On 18 Sep 2009, at 18:25, Raymond O'Donnell wrote:

> On 18/09/2009 16:52, Jonathan Vanasco wrote:
>> I have a table with
>>    name_first
>>    name_middle
>>    name_last
>>
>> if i try concatenating as such:
>>    SELECT
>>        name_first || ' ' || name_middle || ' ' || name_last
>>    FROM
>>        mytable
>>    ;
>>
>> I end up with NULL as the concatenated string whenever any of the
>> referred fields contain a NULL value
>>
>> I tried some text conversion and explicit casting , but that didn't
>> work
>>
>> What am I doing wrong ?
>
> Use the coalesce() function to ensure that you get non-null values,
> thus:
>
>  select
>    coalesce(name_first, '') || ' ' || coalesce (name_middle, '') ....


Or better yet (you won't get double spaces if any value is NULL):

select
    coalesce(name_first, '') || coalesce (' ' || name_middle, '') ....

Alban Hertroys

--
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