OVER(PARTITION BY)函式用法
注意:是這樣麼?
sum(get_money) over(order by
salary range between
5 preceding and 5 following)
這個是salary的範圍 增加5或減少5, 然後計算此範圍內的get_money的值的和
如果換成
sum(get_money) over(order by
last_salary range between
5 preceding and 5 following)
這時是last_salary範圍增加5或者減少5,然後計算此範圍內的get_money的值的和
OVER(PARTITION BY)函式介紹
Oracle從8.1.6開始提供分析函式,分析函式用於計算基於組的某種聚合值,它和聚合函式的不同之處是:對於每個組返回多行,而聚合函式對於每個組只返回一行。
開窗函式指定了分析函式工作的資料視窗大小,這個資料視窗大小可能會隨著行的變化而變化,舉例如下:
1:over後的寫法:
over(order by salary) 按照salary排序進行累計,order by是個預設的開窗函式
over(partition by deptno)按照部門分割槽
2:開窗的視窗範圍:
over(order by salary range between 5 preceding and 5 following):視窗範圍為當前行資料幅度減5加5後的範圍內的。
舉例:
--sum(s)over(order by s range between 2 preceding and 2 following) 表示加2或2的範圍內的求和
adf 3 45 45 --45加2減2即43到47,但是s在這個範圍內只有45
asdf 3 55 55
cfe 2 74 74
3dd 3 78 158 --78在76到80範圍內有78,80,求和得158
fda 1 80 158
gds 2 92 92
ffd 1 95 190
dss 1 95 190
ddd 3 99 198
gf 3 99 198
舉例:
select name,class,s, sum(s)over(order by s rows between 2 preceding and 2 following) mm from t2
adf 3 45 174 (45+55+74=174)
asdf 3 55 252 (45+55+74+78=252)
cfe 2 74 332 (74+55+45+78+80=332)
3dd 3 78 379 (78+74+55+80+92=379)
fda 1 80 419
gds 2 92 440
ffd 1 95 461
dss 1 95 480
ddd 3 99 388
gf 3 99 293
3、與over函式結合的幾個函式介紹
下面以班級成績表t2來說明其應用
t2表資訊如下:cfe 2 74
dss 1 95
ffd 1 95
fda 1 80
gds 2 92
gf 3 99
ddd 3 99
adf 3 45
asdf 3 55
3dd 3 78
select * from
(
select name,class,s,rank()over(partition by class order by s desc) mm from t2
)
where mm=1;
得到的結果是:
dss 1 95 1
ffd 1 95 1
gds 2 92 1
gf 3 99 1
ddd 3 99 1
注意:
1.在求第一名成績的時候,不能用row_number(),因為如果同班有兩個並列第一,row_number()只返回一個結果;
select * from
(
select name,class,s,row_number()over(partition by class order by s desc) mm from t2
)
where mm=1;
1 95 1 --95有兩名但是隻顯示一個
2 92 1
3 99 1 --99有兩名但也只顯示一個
2.rank()和dense_rank()可以將所有的都查詢出來:
如上可以看到採用rank可以將並列第一名的都查詢出來;
rank()和dense_rank()區別:
--rank()是跳躍排序,有兩個第二名時接下來就是第四名;
select name,class,s,rank()over(partition by class order by s desc) mm from t2
dss 1 95 1
ffd 1 95 1
fda 1 80 3 --直接就跳到了第三
gds 2 92 1
cfe 2 74 2
gf 3 99 1
ddd 3 99 1
3dd 3 78 3
asdf 3 55 4
adf 3 45 5
--dense_rank()l是連續排序,有兩個第二名時仍然跟著第三名
select name,class,s,dense_rank()over(partition by class order by s desc) mm from t2
dss 1 95 1
ffd 1 95 1
fda 1 80 2 --連續排序(仍為2)
gds 2 92 1
cfe 2 74 2
gf 3 99 1
ddd 3 99 1
3dd 3 78 2
asdf 3 55 3
adf 3 45 4
--sum()over()的使用
select name,class,s, sum(s)over(partition by class order by s desc) mm from t2 --根據班級進行分數求和
dss 1 95 190 --由於兩個95都是第一名,所以累加時是兩個第一名的相加
ffd 1 95 190
fda 1 80 270 --第一名加上第二名的
gds 2 92 92
cfe 2 74 166
gf 3 99 198
ddd 3 99 198
3dd 3 78 276
asdf 3 55 331
adf 3 45 376
first_value() over()和last_value() over()的使用
--找出這三條電路每條電路的第一條記錄型別和最後一條記錄型別
first_value(res_type) over(PARTITION BY opr_id ORDER BY res_type) low,
last_value(res_type) over(PARTITION BY opr_id ORDER BY res_type rows BETWEEN unbounded preceding AND unbounded following) high
FROM rm_circuit_route
WHERE opr_id IN ('000100190000000000021311','000100190000000000021355','000100190000000000021339')
ORDER BY opr_id;
注:rows BETWEEN unbounded preceding AND unbounded following 的使用
--取last_value時不使用rows BETWEEN unbounded preceding AND unbounded following的結果
first_value(res_type) over(PARTITION BY opr_id ORDER BY res_type) low,
last_value(res_type) over(PARTITION BY opr_id ORDER BY res_type) high
FROM rm_circuit_route
WHERE opr_id IN ('000100190000000000021311','000100190000000000021355','000100190000000000021339')
ORDER BY opr_id;
如下圖可以看到,如果不使用
取出該電路的第一條記錄,加上ignore nulls後,如果第一條是判斷的那個欄位是空的,則預設取下一條,結果如下所示:
lag(expresstion,<offset>,<default>)
with a as
(select 1 id,'a' name from dual
union
select 2 id,'b' name from dual
union
select 3 id,'c' name from dual
union
select 4 id,'d' name from dual
union
select 5 id,'e' name from dual
)
select id,name,lag(id,1,'')over(order by name) from a;
--lead() over()函式用法(取出後N行資料)
lead(expresstion,<offset>,<default>)
with a as
(select 1 id,'a' name from dual
union
select 2 id,'b' name from dual
union
select 3 id,'c' name from dual
union
select 4 id,'d' name from dual
union
select 5 id,'e' name from dual
)
select id,name,lead(id,1,'')over(order by name) from a;
--ratio_to_report(a)函式用法 Ratio_to_report() 括號中就是分子,over() 括號中就是分母
with a as (select 1 a from dual
union all
select 1 a from dual
union all
select 1 a from dual
union all
select 2 a from dual
union all
select 3 a from dual
union all
select 4 a from dual
union all
select 4 a from dual
union all
select 5 a from dual
)
select a, ratio_to_report(a)over(partition by a) b from a
order by a;
with a as (select 1 a from dual
union all
select 1 a from dual
union all
select 1 a from dual
union all
select 2 a from dual
union all
select 3 a from dual
union all
select 4 a from dual
union all
select 4 a from dual
union all
select 5 a from dual
)
select a, ratio_to_report(a)over() b from a --分母預設就是整個佔比
order by a;
with a as (select 1 a from dual
union all
select 1 a from dual
union all
select 1 a from dual
union all
select 2 a from dual
union all
select 3 a from dual
union all
select 4 a from dual
union all
select 4 a from dual
union all
select 5 a from dual
)
select a, ratio_to_report(a)over() b from a
group by a order by a;--分組後的佔比
SELECT a.deptno,
a.ename,
a.sal,
a.r,
b.n,
(a.r-1)/(n-1) pr1,
percent_rank() over(PARTITION BY a.deptno ORDER BY a.sal) pr2
FROM (SELECT deptno,
ename,
sal,
rank() over(PARTITION BY deptno ORDER BY sal) r --計算出在組中的排名序號
FROM emp
ORDER BY deptno, sal) a,
(SELECT deptno, COUNT(1) n FROM emp GROUP BY deptno) b --按部門計算每個部門的所有成員數
WHERE a.deptno = b.deptno;
如下所示自己計算的pr1與通過percent_rank函式得到的值是一樣的:
SELECT a.deptno,
a.ename,
a.sal,
a.r,
b.n,
c.rn,
(a.r + c.rn - 1) / n pr1,
cume_dist() over(PARTITION BY a.deptno ORDER BY a.sal) pr2
FROM (SELECT deptno,
ename,
sal,
rank() over(PARTITION BY deptno ORDER BY sal) r
FROM emp
ORDER BY deptno, sal) a,
(SELECT deptno, COUNT(1) n FROM emp GROUP BY deptno) b,
(SELECT deptno, r, COUNT(1) rn,sal
FROM (SELECT deptno,sal,
rank() over(PARTITION BY deptno ORDER BY sal) r
FROM emp)
GROUP BY deptno, r,sal
ORDER BY deptno) c --c表就是為了得到每個部門員工工資的一樣的個數
WHERE a.deptno = b.deptno
AND a.deptno = c.deptno(+)
AND a.sal = c.sal;
如下,輸入百分比為0.7,因為0.7介於0.6和0.8之間,因此返回的結果就是0.6對應的sal的1500加上0.8對應的sal的1600平均
SELECT ename,
sal,
deptno,
percentile_cont(0.7) within GROUP(ORDER BY sal) over(PARTITION BY deptno) "Percentile_Cont",
percent_rank() over(PARTITION BY deptno ORDER BY sal) "Percent_Rank"
FROM emp
WHERE deptno IN (30, 60);
SELECT ename,
sal,
deptno,
percentile_cont(0.6) within GROUP(ORDER BY sal) over(PARTITION BY deptno) "Percentile_Cont",
percent_rank() over(PARTITION BY deptno ORDER BY sal) "Percent_Rank"
FROM emp
WHERE deptno IN (30, 60);
注意:本函式與PERCENTILE_CONT的區別在找不到對應的分佈值時返回的替代值的計算方法不同
SAMPLE:下例中0.7的分佈值在部門30中沒有對應的Cume_Dist值,所以就取下一個分佈值0.83333333所對應的SALARY來替代
SELECT ename,
sal,
deptno,
percentile_disc(0.7) within GROUP(ORDER BY sal) over(PARTITION BY deptno) "Percentile_Disc",
cume_dist() over(PARTITION BY deptno ORDER BY sal) "Cume_Dist"
FROM emp
WHERE deptno IN (30, 60);
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