postgresql - POSTGRES COALESCE(NULLIF(c.name,''), 'unassigned') not working -

no version of character varying field return null if there isn't value... it's frustrating

case when coalesce(nullif(e.name,''),'unassigned') null 'unassigned' else a.name end

was final test , still returns null unless field has value

it's character varying(255)

coalesce(a.name,'unassigned') // won't work nullif(a.name,'') // won't work nullif(a.name,null) // won't work coalesce(nullif(a.name,''),'unassigned') // won't work 

however instant use 0 works..

what's that?

it's character varying(255) field , set default null

as matter of point build of table column is

name varying character(255) default(null) 

so know it's entering null , i've done

select * <tbl> name null; , of course, return null rows a.name... what's deal this?

ok... deciding answer me with:

coalesce(nullif(e.name,''),'unassigned') null... 

this method never work on return of "no records" , stored procedure creates materialized view, i'm polling via nested queries - possible column have 0 (as default id = other_id) nested query return no rows. when no row returned, functions of coalesce or nullif never execute. row have returned in order functions act upon row values... i've never heard of table pk auto-incremented field starting @ 0 , starting @ 1 resultset of "no records returned" return null value materialized view column.

the query run afterward poll rows materialized view function coalesce(etc etc) because there actual null value in column.