Re: How concat 3 strings if 2 are not empty?

No.
B should only appear if A and C are not empty.
B is just a filler.

Thanks
Andreas

A. Kretschmer schrieb:
> In response to Andreas :
>   
>> I'd like a function that concats 3 string parameters on condition the 
>> 1st and 3rd are NOT empty or NULL.
>> xCat (s1, s2, s3)
>> s2 would be a connector that appears only if s1 and s3 are set.
>>
>> NULL and an empty string '' should be handled the same.
>>
>> e.g.
>> 'PostgreSQL',  ' is ', ' great'    -->     'PostgreSQL is great'
>> NULL,  ' is ', ' great'              -->     'great'
>> 'PostgreSQL',  ' is ', NULL    -->     'PostgreSQL'
>> NULL,  ' is ', NULL              -->     NULL
>> 'PostgreSQL',  NULL, ' great'    -->     'PostgreSQL great'
>>     
>
> Something like that?
>
> test=*# select a,b,c, length(a), length(b), length(c) from string ;
>      a      | b  |   c   | length | length | length
> ------------+----+-------+--------+--------+--------
>  PostgreSQL | is | great |     10 |      2 |      5
>  PostgreSQL | is |       |     10 |      2 |
>  PostgreSQL |    |       |     10 |        |
>             | is |       |        |      2 |
>             | is |       |      0 |      2 |
>             | is |       |      0 |      2 |      0
> (6 rows)
>
> test=*#
> test=*# select case when (a is null and c is null) or (a = '' and c = '') then null else coalesce(a,'') ||
coalesce(b,'')||coalesce(c,'')end from string;
 
>        case
> -------------------
>  PostgreSQLisgreat
>  PostgreSQLis
>  PostgreSQL
>
>  is
>
> (6 rows)
>
>