SQL> ed
Wrote file afiedt.buf

  1  with DOCLIST(DOC_ID,DESIGNATIO,DOC_STATUS) as(
  2  select 1,'xpd 11',17 from dual union all
  3  select 6,'xrk 73',20 from dual union all
  4  select 8,'xrk ??',21 from dual union all
  5  select 9,'xpd 12',0 from dual )
  6  , USERS(USER_ID,FULLNAME) as(
  7  select 17,'Stax' from dual union all
  8  select 20,'bors' from dual union all
  9  select 27,'Tera' from dual)
 10  select
 11   d.DOC_ID
 12   ,d.DESIGNATIO
 13   ,decode(d.DOC_STATUS,0,'Сдан',u.FULLNAME) FULLNAME
 14  from
 15   DOCLIST d LEFT JOIN USERS u ON u.USER_ID = d.DOC_STATUS
 16* order by 1
SQL> /

    DOC_ID DESIGN FULL
---------- ------ ----
         1 xpd 11 Stax
         6 xrk 73 bors
         8 xrk ??
         9 xpd 12 Сдан

  1  with DOCLIST(DOC_ID,DESIGNATIO,DOC_STATUS,DESIGNERID) as(
  2    select 1,'xpd_11',17,27 from dual union all
  3    select 6,'xrk_73',20,0 from dual union all
  4    select 8,'xrk_??',21,0 from dual union all
  5    select 9,'xpd_12',0,20 from dual )
  6  ,USERS(USER_ID,FULLNAME) as(
  7    select 17,'Stax' from dual union all
  8    select 20,'bors' from dual union all
  9    select 27,'Tera' from dual)
 10  select
 11    d.DOC_ID
 12   ,d.DESIGNATIO
 13   ,decode(d.DOC_STATUS,0,'Сдан',u.FULLNAME) FULLNAME_STAT
 14   ,s.FULLNAME FULLNAME_DES
 15  from
 16   DOCLIST d
 17  LEFT JOIN USERS u ON u.USER_ID = d.DOC_STATUS
 18  LEFT JOIN USERS s ON s.USER_ID = d.DESIGNERID
 19* order by 1
SQL> /

    DOC_ID DESIGN FULLNAME_STAT   FULLNAME_DES
---------- ------ --------------- ---------------
         1 xpd_11 Stax            Tera
         6 xrk_73 bors
         8 xrk_??
         9 xpd_12 Сдан            bors

SQL>