select flow_id,rw from (select t.flow_id ,rownum as rw from apex_030200.wwv_flow_list_templates t) where rw >= 5
1.rownum只能用<如果使用>加別名
2.子查詢引用只能在查詢出的結果中引用，比如子查詢沒有查出flow_id,外層不能用，另外外層不能引用內層的t
3.薪水前三名，內層查出薪水 order desc的虛表外層使用rownum<3
4.merge可以實現存在數據就update不存在你就insert
merge into product a
using （select 1717 product_id, '002' req_no from dual b）
on (a.product_id = b.product.id and a.req_no = b.req.no)
when matched then
update set product name = ''.....................
when not matched then
insert () values ()
5.start with connect by 可以查詢出一組樹的數據,注意最后connect by的條件（父節點=子節點 向上查詢 反之向下查詢）
可以order排序，可以加入兩棵樹（or），也可以加入where條件
select * from emp
where......
start with empnc = 7369 or empnc = 7204(注意不能用and )
connect by prior mgr = empno
order by ...
6 份額（查詢某數據占有總數據的百分比）
select t.empno,t.ename,t.sal,
100*round(sal/sum(sal) over(),5)
from emp t
7 連續求和(同名分為同組 累加)
select t.empno,t.ename,t.sal,
sum(sal) over(order by sal)
from emp t
8.帶條件的連續求和（分部門連續求和）
select t.empno,t.ename,t.sal,t.deptno,
sum(sal) over(partition by t.deptno order by sal)
from emp t
9.分部門總和（取出orderby）
select t.empno,t.ename,t.sal,t.deptno,
sum(sal) over(partition by t.deptno)
from emp t
10工資的分組查詢份額（總數的百分比）帶上部門分組
select t.empno,t.ename,t.sal,t.deptno,
100*round(sal/sum(sal) over (partition by t.deptno),4)
from emp t
注意這里查詢的是“”分組“，因此這里查詢的是變成一組為一個100%，查詢的是一個部門中員工在本部分所占用的薪水比例
11分組查詢出單一條件並分級（查詢某一個部門的薪水的級別）注意rank()和row_number()的區別 rank是跳躍性並列(1.1.3.3.5) row_number(1.2.3.4.5)
select t.*,ROW_NUMBER() over(partition by t.deptno order by t.sal desc) rank from emp t
12“總”。。。。。。這個字眼一般使用group by（區分於over（partition by order by））
按部門分組查詢部門的總薪水
select sum(t.sal),t.deptno from emp t group by t.deptno
13 總的基礎上再次分組 group by + rollup
select sum(t.sal),t.deptno from emp t group by rollup (t.deptno)匯總后將總和進行求和
select sum(t.sal),t.job,t.deptno from emp t group by rollup (t.deptno,t.job)注意多個rollup其實只有第一個參數有效
14cube 連接在order by后面（代替ROLLUP） rollup升級版 全部分組
15grouping實現不用java代碼就可以對oracle 查詢出的null字段進行賦值 0 本身結果 1合計結果
select sum(t.sal),t.deptno,
(case
when((grouping(t.job)=1 and grouping(t.deptno)=0)) then '部門小計'
when((grouping(t.job)=1 and grouping(t.deptno)=1)) then '部門總計'
else t.job end) as
job from emp t group by rollup (t.deptno,t.job)
16分組后的字段累加(比如按照員工名稱，根據月份分組，實現自1月份到12月份工資累加，即二月份是 1月 + 2月 。。)
select t.empno, t.ename, t.sal, sum(sal) over (partition by t.ename order by t.sal desc) from emp t
17分組最高值 最低值 平均值 使用 max() over(partition by order by)代替sum() 還可以用min() avg()
18select * from v$transaction 查看事務
19多層分組函數和子查詢之間的沖突問題
select a.CREATOR, a.count_Sum, b.full_name, b.dept_code, b.area_code
from (select temp.c CREATOR, count(temp.c) as count_Sum
from (select t.ca,
c.lv,
instr(t.ca, ',', 1, c.lv) + 1,
substr(t.ca,
instr(t.ca, ',', 1, c.lv) + 1,
instr(t.ca, ',', 1, c.lv + 1) -
(instr(t.ca, ',', 1, c.lv) + 1)) AS c
from (select ',' || checker || ',' AS ca,
checker,
LENGTH(checker),
length(checker || ','),
REPLACE(checker, ','),
length(REPLACE(checker, ',')),
nvl(length(REPLACE(checker, ',')), 0),
length(checker || ',') -
nvl(length(REPLACE(checker, ',')), 0) AS cnt
FROM wm_time_info a
where a.check_result != 1) t,
(select LEVEL lv from dual CONNECT BY LEVEL <= 100) c
where c.lv <= t.cnt) temp
group by temp.c) a,
base_user b
where a.CREATOR = b.user_code
外層查詢和內層分組沖突
--select a.CREATOR, a.count_Sum ,b.full_name,b.dept_code,b.area_code from (
select o.CREATOR,
count(o.CREATOR) as count_Sum,
FULLNAME,
DEPTCODE,
AREACODE
from (select temp.c CREATOR,
b.full_name FULLNAME,
b.dept_code DEPTCODE,
b.area_code AREACODE,
work_date
from (select work_date,
t.ca,
c.lv,
instr(t.ca, ',', 1, c.lv) + 1,
substr(t.ca,
instr(t.ca, ',', 1, c.lv) + 1,
instr(t.ca, ',', 1, c.lv + 1) -
(instr(t.ca, ',', 1, c.lv) + 1)) AS c
from (
---
select work_date,
',' || checker || ',' AS ca,
checker,
LENGTH(checker),
length(checker || ','),
REPLACE(checker, ','),
length(REPLACE(checker, ',')),
nvl(length(REPLACE(checker, ',')), 0),
length(checker || ',') -
nvl(length(REPLACE(checker, ',')), 0) AS cnt
FROM wm_time_info a
where a.check_result != 1
---
) t,
(select LEVEL lv from dual CONNECT BY LEVEL <= 100) c
where c.lv <= t.cnt) temp,
base_user b
where temp.c = b.user_code) o
--where work_date >='2016-01-10'
group by o.CREATOR, FULLNAME, DEPTCODE, AREACODE
--) a ,base_user b where a.CREATOR = b.user_code
20 注意 本條select中的分組和子查詢都不可以作為函數的參數傳入