部分常用sql，適用於oracle

上一個月時間：

to_char(add_months(sysdate, -1),'yyyymm')

字符串補零：

to_char(0.68,'FM9999990.0099') 

近10天：

select to_char((to_date(to_char(sysdate,'yyyymmdd'),'yyyymmdd') - 10) + rownum,'yyyymmdd') rq from dual a connect bylevel <= 10

同列按順序合併：

selectid, sys_connect_by_path(name, ',')
  from (select id,
               name,
               row_number() over(partitionby id order by name) rn,
               count(*) over(partitionby id) cnt
          from test1) a
 where level = cnt
 start with rn = 1
connect by prior id = id
       and prior rn = rn – 1

生成32位隨機數：

 select  sys_guid() from dual

CLOB字段轉換成varchar:

dbms_lob.substr(clobcolumn,4000)