你可以使用to_char(sysdate, 'fmday')来返回当天的字符串名称：

where order_date =  
  case
    when to_char(sysdate, 'fmday', 'nls_date_language=AMERICAN') = 'friday' then trunc(sysdate) + 3
    when to_char(sysdate, 'fmday', 'nls_date_language=AMERICAN') = 'saturday' then trunc(sysdate) + 2
    else trunc(sysdate) + 1
  end

更好：

where order_date = 
  trunc(sysdate) + case
    when to_char(sysdate, 'fmday', 'nls_date_language=AMERICAN') = 'friday' then 3
    when to_char(sysdate, 'fmday', 'nls_date_language=AMERICAN') = 'saturday' then 2
    else 1
  end

要从语句中获得结果，请使用以下语句。

where order_date = 
(Select 
CASE WHEN (1 + TRUNC (SYSDATE) - TRUNC (SYSDATE, 'IW')) < 5 
  THEN TRUNC (SYSDATE) + 1 
  ELSE TRUNC ((SYSDATE + 4), 'IW')  
END from dual);

您可以用途：

WHERE order_date = TRUNC(SYSDATE)
                   + CASE TRUNC(SYSDATE) - TRUNC (SYSDATE, 'IW')
                     WHEN 4 THEN 3 -- Add 3 days on Friday
                     WHEN 5 THEN 2 -- Add 2 days on Saturday
                            ELSE 1 -- Add 1 day on all other days of the week
                     END