else if decode oracle

SELECT col1, col2, 
       CASE 
          WHEN col3 > 1 AND col3 <2 
             THEN '1' 
          WHEN col3 > 2 AND col3 <3 
             THEN '2' 
          WHEN col3 > 3 AND col3 <4 
             THEN '3' 
          ELSE '4' 
       END mylevel 
FROM table1 

select case 
       when 
          nsrsbh='330165737758262'
       then
          nsrsbh
       when 
          nsrsbh='330106745808709'  
       then 
         nsrsbh 
       else 
          '99999'
       end 
from WS_TDS_SQ

decode(条件,值1,返回值1,值2,返回值2,...值n,返回值n,缺省值)
decode(字段或字段的运算，值1，值2，值3）
ELECT DECODE (value, <if this value>, <return this value>) FROM table

select decode(nsrsbh,'330165737758262',nsrsbh,'330106745808709',nsrsbh,0) from WS_TDS_SQ
select decode(nsrsbh,'330165737758262','6','9') from WS_TDS_SQ