Oracle分析函式參考手冊(轉)一

wangkxxe發表於2009-08-12

本文如果未指明,預設是在HR使用者下執行例子。
開窗函式的的理解:
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:
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
over(order by salary range between 50 preceding and 150 following)
每行對應的資料視窗是之前行幅度值不超過50,之後行幅度值不超過150
over(order by salary rows between 50 preceding and 150 following)
每行對應的資料視窗是之前50行,之後150行
over(order by salary rows between unbounded preceding and unbounded following)
每行對應的資料視窗是從第一行到最後一行,等效:
over(order by salary range between unbounded preceding and unbounded following)

主要參考資料:《expert one-on-one》 Tom Kyte 《Oracle9i SQL Reference》第6章


AVG
功能描述:用於計算一個組和資料視窗內表示式的平均值。
SAMPLE:下面的例子中列c_mavg計算員工表中每個員工的平均薪水報告,該平均值由當前員工和與之具有相同經理的前一個和後一個三者的平均數得來;

SELECT manager_id, last_name, hire_date, salary,
AVG(salary) OVER (PARTITION BY manager_id ORDER BY hire_date
ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) AS c_mavg
FROM employees;

MANAGER_ID LAST_NAME HIRE_DATE SALARY C_MAVG
---------- ------------------------- --------- ---------- ----------
100 Kochhar 21-SEP-89 17000 17000
100 De Haan 13-JAN-93 17000 15000
100 Raphaely 07-DEC-94 11000 11966.6667
100 Kaufling 01-MAY-95 7900 10633.3333
100 Hartstein 17-FEB-96 13000 9633.33333
100 Weiss 18-JUL-96 8000 11666.6667
100 Russell 01-OCT-96 14000 11833.3333

CORR
功能描述:返回一對錶達式的相關係數,它是如下的縮寫:
COVAR_POP(expr1,expr2)/STDDEV_POP(expr1)*STDDEV_POP(expr2))
從統計上講,相關性是變數之間關聯的強度,變數之間的關聯意味著在某種程度
上一個變數的值可由其它的值進行預測。透過返回一個-1~1之間的一個數, 相關
係數給出了關聯的強度,0表示不相關。
SAMPLE:下例返回1998年月銷售收入和月單位銷售的關係的累積係數(本例在SH使用者下執行)

SELECT t.calendar_month_number,
CORR (SUM(s.amount_sold), SUM(s.quantity_sold))
OVER (ORDER BY t.calendar_month_number) as CUM_CORR
FROM sales s, times t
WHERE s.time_id = t.time_id AND calendar_year = 1998
GROUP BY t.calendar_month_number
ORDER BY t.calendar_month_number;

CALENDAR_MONTH_NUMBER CUM_CORR
--------------------- ----------
1
2 1
3 .994309382
4 .852040875
5 .846652204
6 .871250628
7 .910029803
8 .917556399
9 .920154356
10 .86720251
11 .844864765
12 .903542662


COVAR_POP
功能描述:返回一對錶達式的總體協方差。
SAMPLE:下例CUM_COVP返回定價和最小產品價格的累積總體協方差

SELECT product_id, supplier_id,
COVAR_POP(list_price, min_price)
OVER (ORDER BY product_id, supplier_id) AS CUM_COVP,
COVAR_SAMP(list_price, min_price)
OVER (ORDER BY product_id, supplier_id) AS CUM_COVS
FROM product_information p
WHERE category_id = 29
ORDER BY product_id, supplier_id;

PRODUCT_ID SUPPLIER_ID CUM_COVP CUM_COVS
---------- ----------- ---------- ----------
1774 103088 0
1775 103087 1473.25 2946.5
1794 103096 1702.77778 2554.16667
1825 103093 1926.25 2568.33333
2004 103086 1591.4 1989.25
2005 103086 1512.5 1815
2416 103088 1475.97959 1721.97619
.
.


COVAR_SAMP
功能描述:返回一對錶達式的樣本協方差
SAMPLE:下例CUM_COVS返回定價和最小產品價格的累積樣本協方差

SELECT product_id, supplier_id,
COVAR_POP(list_price, min_price)
OVER (ORDER BY product_id, supplier_id) AS CUM_COVP,
COVAR_SAMP(list_price, min_price)
OVER (ORDER BY product_id, supplier_id) AS CUM_COVS
FROM product_information p
WHERE category_id = 29
ORDER BY product_id, supplier_id;

PRODUCT_ID SUPPLIER_ID CUM_COVP CUM_COVS
---------- ----------- ---------- ----------
1774 103088 0
1775 103087 1473.25 2946.5
1794 103096 1702.77778 2554.16667
1825 103093 1926.25 2568.33333
2004 103086 1591.4 1989.25
2005 103086 1512.5 1815
2416 103088 1475.97959 1721.97619
.
.


COUNT
功能描述:對一組內發生的事情進行累積計數,如果指定*或一些非空常數,count將對所有行計數,如果指定一個表示式,count返回表示式非空賦值的計數,當有相同值出現時,這些相等的值都會被納入被計算的值;可以使用DISTINCT來記錄去掉一組中完全相同的資料後出現的行數。
SAMPLE:下面例子中計算每個員工在按薪水排序中當前行附近薪水在[n-50,n+150]之間的行數,n表示當前行的薪水
例如,Philtanker的薪水2200,排在他之前的行中薪水大於等於2200-50的有1行,排在他之後的行中薪水小於等於2200+150的行沒有,所以count計數值cnt3為2(包括自己當前行);cnt2值相當於小於等於當前行的SALARY值的所有行數

SELECT last_name, salary, COUNT(*) OVER () AS cnt1,
COUNT(*) OVER (ORDER BY salary) AS cnt2,
COUNT(*) OVER (ORDER BY salary RANGE BETWEEN 50 PRECEDING
AND 150 FOLLOWING) AS cnt3 FROM employees;

LAST_NAME SALARY CNT1 CNT2 CNT3
------------------------- ---------- ---------- ---------- ----------
Olson 2100 107 1 3
Markle 2200 107 3 2
Philtanker 2200 107 3 2
Landry 2400 107 5 8
Gee 2400 107 5 8
Colmenares 2500 107 11 10
Patel 2500 107 11 10
.
.


CUME_DIST
功能描述:計算一行在組中的相對位置,CUME_DIST總是返回大於0、小於或等於1的數,該數表示該行在N行中的位置。例如,在一個3行的組中,返回的累計分佈值為1/3、2/3、3/3
SAMPLE:下例中計算每個工種的員工按薪水排序依次累積出現的分佈百分比

SELECT job_id, last_name, salary, CUME_DIST()
OVER (PARTITION BY job_id ORDER BY salary) AS cume_dist
FROM employees WHERE job_id LIKE 'PU%';

JOB_ID LAST_NAME SALARY CUME_DIST
---------- ------------------------- ---------- ----------
PU_CLERK Colmenares 2500 .2
PU_CLERK Himuro 2600 .4
PU_CLERK Tobias 2800 .6
PU_CLERK Baida 2900 .8
PU_CLERK Khoo 3100 1
PU_MAN Raphaely 11000 1


DENSE_RANK
功能描述:根據ORDER BY子句中表示式的值,從查詢返回的每一行,計算它們與其它行的相對位置。組內的資料按ORDER BY子句排序,然後給每一行賦一個號,從而形成一個序列,該序列從1開始,往後累加。每次ORDER BY表示式的值發生變化時,該序列也隨之增加。有同樣值的行得到同樣的數字序號(認為null時相等的)。密集的序列返回的時沒有間隔的數
SAMPLE:下例中計算每個員工按部門分割槽再按薪水排序,依次出現的序列號(注意與RANK函式的區別)

SELECT d.department_id , e.last_name, e.salary, DENSE_RANK()
OVER (PARTITION BY e.department_id ORDER BY e.salary) as drank
FROM employees e, departments d
WHERE e.department_id = d.department_id
AND d.department_id IN ('60', '90');

DEPARTMENT_ID LAST_NAME SALARY DRANK
------------- ------------------------- ---------- ----------
60 Lorentz 4200 1
60 Austin 4800 2
60 Pataballa 4800 2
60 Ernst 6000 3
60 Hunold 9000 4
90 Kochhar 17000 1
90 De Haan 17000 1
90 King 24000 2


FIRST
功能描述:從DENSE_RANK返回的集合中取出排在最前面的一個值的行(可能多行,因為值可能相等),因此完整的語法需要在開始處加上一個集合函式以從中取出記錄
SAMPLE:下面例子中DENSE_RANK按部門分割槽,再按佣金commission_pct排序,FIRST取出佣金最低的對應的所有行,然後前面的MAX函式從這個集合中取出薪水最低的值;LAST取出佣金最高的對應的所有行,然後前面的MIN函式從這個集合中取出薪水最高的值
SELECT last_name, department_id, salary,
MIN(salary) KEEP (DENSE_RANK FIRST ORDER BY commission_pct)
OVER (PARTITION BY department_id) "Worst",
MAX(salary) KEEP (DENSE_RANK LAST ORDER BY commission_pct)
OVER (PARTITION BY department_id) "Best"
FROM employees
WHERE department_id in (20,80)
ORDER BY department_id, salary;

LAST_NAME DEPARTMENT_ID SALARY Worst Best
------------------------- ------------- ---------- ---------- ----------
Fay 20 6000 6000 13000
Hartstein 20 13000 6000 13000
Kumar 80 6100 6100 14000
Banda 80 6200 6100 14000
Johnson 80 6200 6100 14000
Ande 80 6400 6100 14000
Lee 80 6800 6100 14000
Tuvault 80 7000 6100 14000
Sewall 80 7000 6100 14000
Marvins 80 7200 6100 14000
Bates 80 7300 6100 14000
.
.
.


FIRST_VALUE
功能描述:返回組中資料視窗的第一個值。
SAMPLE:下面例子計算按部門分割槽按薪水排序的資料視窗的第一個值對應的名字,如果薪水的第一個值有多個,則從多個對應的名字中取預設排序的第一個名字

SELECT department_id, last_name, salary, FIRST_VALUE(last_name)
OVER (PARTITION BY department_id ORDER BY salary ASC ) AS lowest_sal
FROM employees
WHERE department_id in(20,30);

DEPARTMENT_ID LAST_NAME SALARY LOWEST_SAL
------------- ------------------------- ---------- --------------
20 Fay 6000 Fay
20 Hartstein 13000 Fay
30 Colmenares 2500 Colmenares
30 Himuro 2600 Colmenares
30 Tobias 2800 Colmenares
30 Baida 2900 Colmenares
30 Khoo 3100 Colmenares
30 Raphaely 11000 Colmenares


LAG
功能描述:可以訪問結果集中的其它行而不用進行自連線。它允許去處理遊標,就好像遊標是一個陣列一樣。在給定組中可參考當前行之前的行,這樣就可以從組中與當前行一起選擇以前的行。Offset是一個正整數,其預設值為1,若索引超出視窗的範圍,就返回預設值(預設返回的是組中第一行),其相反的函式是LEAD
SAMPLE:下面的例子中列prev_sal返回按hire_date排序的前1行的salary值

SELECT last_name, hire_date, salary,
LAG(salary, 1, 0) OVER (ORDER BY hire_date) AS prev_sal
FROM employees
WHERE job_id = 'PU_CLERK';

LAST_NAME HIRE_DATE SALARY PREV_SAL
------------------------- ---------- ---------- ----------
Khoo 18-5月 -95 3100 0
Tobias 24-7月 -97 2800 3100
Baida 24-12月-97 2900 2800
Himuro 15-11月-98 2600 2900
Colmenares 10-8月 -99 2500 2600


LAST
功能描述:從DENSE_RANK返回的集合中取出排在最後面的一個值的行(可能多行,因為值可能相等),因此完整的語法需要在開始處加上一個集合函式以從中取出記錄
SAMPLE:下面例子中DENSE_RANK按部門分割槽,再按佣金commission_pct排序,FIRST取出佣金最低的對應的所有行,然後前面的MAX函式從這個集合中取出薪水最低的值;LAST取出佣金最高的對應的所有行,然後前面的MIN函式從這個集合中取出薪水最高的值
SELECT last_name, department_id, salary,
MIN(salary) KEEP (DENSE_RANK FIRST ORDER BY commission_pct)
OVER (PARTITION BY department_id) "Worst",
MAX(salary) KEEP (DENSE_RANK LAST ORDER BY commission_pct)
OVER (PARTITION BY department_id) "Best"
FROM employees
WHERE department_id in (20,80)
ORDER BY department_id, salary;

LAST_NAME DEPARTMENT_ID SALARY Worst Best
------------------------- ------------- ---------- ---------- ----------
Fay 20 6000 6000 13000
Hartstein 20 13000 6000 13000
Kumar 80 6100 6100 14000
Banda 80 6200 6100 14000
Johnson 80 6200 6100 14000
Ande 80 6400 6100 14000
Lee 80 6800 6100 14000
Tuvault 80 7000 6100 14000
Sewall 80 7000 6100 14000
Marvins 80 7200 6100 14000
Bates 80 7300 6100 14000
.
LAST_VALUE
功能描述:返回組中資料視窗的最後一個值。
SAMPLE:下面例子計算按部門分割槽按薪水排序的資料視窗的最後一個值對應的名字,如果薪水的最後一個值有多個,則從多個對應的名字中取預設排序的最後一個名字
SELECT department_id, last_name, salary, LAST_VALUE(last_name)
OVER(PARTITION BY department_id ORDER BY salary) AS highest_sal
FROM employees
WHERE department_id in(20,30);

DEPARTMENT_ID LAST_NAME SALARY HIGHEST_SAL
------------- ------------------------- ---------- ------------
20 Fay 6000 Fay
20 Hartstein 13000 Hartstein
30 Colmenares 2500 Colmenares
30 Himuro 2600 Himuro
30 Tobias 2800 Tobias
30 Baida 2900 Baida
30 Khoo 3100 Khoo
30 Raphaely 11000 Raphaely


LEAD
功能描述:LEAD與LAG相反,LEAD可以訪問組中當前行之後的行。Offset是一個正整數,其預設值為1,若索引超出視窗的範圍,就返回預設值(預設返回的是組中第一行)
SAMPLE:下面的例子中每行的"NextHired"返回按hire_date排序的下一行的hire_date值

SELECT last_name, hire_date,
LEAD(hire_date, 1) OVER (ORDER BY hire_date) AS "NextHired"
FROM employees WHERE department_id = 30;

LAST_NAME HIRE_DATE NextHired
------------------------- --------- ---------
Raphaely 07-DEC-94 18-MAY-95
Khoo 18-MAY-95 24-JUL-97
Tobias 24-JUL-97 24-DEC-97
Baida 24-DEC-97 15-NOV-98
Himuro 15-NOV-98 10-AUG-99
Colmenares 10-AUG-99


MAX
功能描述:在一個組中的資料視窗中查詢表示式的最大值。
SAMPLE:下面例子中dept_max返回當前行所在部門的最大薪水值

SELECT department_id, last_name, salary,
MAX(salary) OVER (PARTITION BY department_id) AS dept_max
FROM employees WHERE department_id in (10,20,30);

DEPARTMENT_ID LAST_NAME SALARY DEPT_MAX
------------- ------------------------- ---------- ----------
10 Whalen 4400 4400
20 Hartstein 13000 13000
20 Fay 6000 13000
30 Raphaely 11000 11000
30 Khoo 3100 11000
30 Baida 2900 11000
30 Tobias 2800 11000
30 Himuro 2600 11000
30 Colmenares 2500 11000


MIN
功能描述:在一個組中的資料視窗中查詢表示式的最小值。
SAMPLE:下面例子中dept_min返回當前行所在部門的最小薪水值

SELECT department_id, last_name, salary,
MIN(salary) OVER (PARTITION BY department_id) AS dept_min
FROM employees WHERE department_id in (10,20,30);

DEPARTMENT_ID LAST_NAME SALARY DEPT_MIN
------------- ------------------------- ---------- ----------
10 Whalen 4400 4400
20 Hartstein 13000 6000
20 Fay 6000 6000
30 Raphaely 11000 2500
30 Khoo 3100 2500
30 Baida 2900 2500
30 Tobias 2800 2500
30 Himuro 2600 2500
30 Colmenares 2500 2500


NTILE
功能描述:將一個組分為"表示式"的雜湊表示,例如,如果表示式=4,則給組中的每一行分配一個數(從1到4),如果組中有20行,則給前5行分配1,給下5行分配2等等。如果組的基數不能由表示式值平均分開,則對這些行進行分配時,組中就沒有任何percentile的行數比其它percentile的行數超過一行,最低的percentile是那些擁有額外行的percentile。例如,若表示式=4,行數=21,則percentile=1的有5行,percentile=2的有5行等等。
SAMPLE:下例中把6行資料分為4份

SELECT last_name, salary,
NTILE(4) OVER (ORDER BY salary DESC) AS quartile FROM employees
WHERE department_id = 100;

LAST_NAME SALARY QUARTILE
------------------------- ---------- ----------
Greenberg 12000 1
Faviet 9000 1
Chen 8200 2
Urman 7800 2
Sciarra 7700 3
Popp 6900 4


PERCENT_RANK
功能描述:和CUME_DIST(累積分配)函式類似,對於一個組中給定的行來說,在計算那行的序號時,先減1,然後除以n-1(n為組中所有的行數)。該函式總是返回0~1(包括1)之間的數。
SAMPLE:下例中如果Khoo的salary為2900,則pr值為0.6,因為RANK函式對於等值的返回序列值是一樣的

SELECT department_id, last_name, salary,
PERCENT_RANK()
OVER (PARTITION BY department_id ORDER BY salary) AS pr
FROM employees
WHERE department_id < 50
ORDER BY department_id,salary;

DEPARTMENT_ID LAST_NAME SALARY PR
------------- ------------------------- ---------- ----------
10 Whalen 4400 0
20 Fay 6000 0
20 Hartstein 13000 1
30 Colmenares 2500 0
30 Himuro 2600 0.2
30 Tobias 2800 0.4
30 Baida 2900 0.6
30 Khoo 3100 0.8
30 Raphaely 11000 1
40 Mavris 6500 0


PERCENTILE_CONT
功能描述:返回一個與輸入的分佈百分比值相對應的資料值,分佈百分比的計算方法見函式PERCENT_RANK,如果沒有正好對應的資料值,就透過下面演算法來得到值:
RN = 1+ (P*(N-1)) 其中P是輸入的分佈百分比值,N是組內的行數
CRN = CEIL(RN) FRN = FLOOR(RN)
if (CRN = FRN = RN) then
(value of expression from row at RN)
else
(CRN - RN) * (value of expression for row at FRN) +
(RN - FRN) * (value of expression for row at CRN)
注意:本函式與PERCENTILE_DISC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:在下例中,對於部門60的Percentile_Cont值計算如下:
P=0.7 N=5 RN =1+ (P*(N-1)=1+(0.7*(5-1))=3.8 CRN = CEIL(3.8)=4
FRN = FLOOR(3.8)=3
(4 - 3.8)* 4800 + (3.8 - 3) * 6000 = 5760

SELECT last_name, salary, department_id,
PERCENTILE_CONT(0.7) WITHIN GROUP (ORDER BY salary)
OVER (PARTITION BY department_id) "Percentile_Cont",
PERCENT_RANK()
OVER (PARTITION BY department_id ORDER BY salary) "Percent_Rank"
FROM employees WHERE department_id IN (30, 60);

LAST_NAME SALARY DEPARTMENT_ID Percentile_Cont Percent_Rank
------------------------- ---------- ------------- --------------- ------------
Colmenares 2500 30 3000 0
Himuro 2600 30 3000 0.2
Tobias 2800 30 3000 0.4
Baida 2900 30 3000 0.6
Khoo 3100 30 3000 0.8
Raphaely 11000 30 3000 1
Lorentz 4200 60 5760 0
Austin 4800 60 5760 0.25
Pataballa 4800 60 5760 0.25
Ernst 6000 60 5760 0.75
Hunold 9000 60 5760 1


PERCENTILE_DISC
功能描述:返回一個與輸入的分佈百分比值相對應的資料值,分佈百分比的計算方法見函式CUME_DIST,如果沒有正好對應的資料值,就取大於該分佈值的下一個值。
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 last_name, salary, department_id,
PERCENTILE_DISC(0.7) WITHIN GROUP (ORDER BY salary )
OVER (PARTITION BY department_id) "Percentile_Disc",
CUME_DIST() OVER (PARTITION BY department_id ORDER BY salary) "Cume_Dist"
FROM employees
WHERE department_id in (30, 60);

LAST_NAME SALARY DEPARTMENT_ID Percentile_Disc Cume_Dist
------------------------- ---------- ------------- --------------- ----------
Colmenares 2500 30 3100 .166666667
Himuro 2600 30 3100 .333333333
Tobias 2800 30 3100 .5
Baida 2900 30 3100 .666666667
Khoo 3100 30 3100 .833333333
Raphaely 11000 30 3100 1
Lorentz 4200 60 6000 .2
Austin 4800 60 6000 .6
Pataballa 4800 60 6000 .6
Ernst 6000 60 6000 .8
Hunold 9000 60 6000 1

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