【正文】 2000 1 Faviet 9000 1 Chen 8200 2 Urman 7800 2 Sciarra 7700 3 Popp 6900 4 86。PERCENT_RANK 功能描述：和CUME_DIST（累積分配）函數(shù)類(lèi)似，對(duì)于一個(gè)組中給定的行來(lái)說(shuō)，在計(jì)算那行的序號(hào)時(shí)，先減1，然后除以n1（n為組中所有的行數(shù)）。該函數(shù)總是返回0～1（包括1）之間的數(shù)。 SAMPLE：下例中如果Khoo的salary為2900，因?yàn)镽ANK函數(shù)對(duì)于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 30 Tobias 2800 30 Baida 2900 30 Khoo 3100 30 Raphaely 11000 1 40 Mavris 6500 0 ? 87。PERCENTILE_CONT 功能描述：返回一個(gè)與輸入的分布百分比值相對(duì)應(yīng)的數(shù)據(jù)值，分布百分比的計(jì)算方法見(jiàn)函數(shù)PERCENT_RANK，如果沒(méi)有正好對(duì)應(yīng)的數(shù)據(jù)值，就通過(guò)下面算法來(lái)得到值： RN = 1+ (P*(N1)) 其中P是輸入的分布百分比值，N是組內(nèi)的行數(shù) 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：本函數(shù)與PERCENTILE_DISC的區(qū)別在找不到對(duì)應(yīng)的分布值時(shí)返回的替代值的計(jì)算方法不同 SAMPLE：在下例中，對(duì)于部門(mén)60的Percentile_Cont值計(jì)算如下： P= N=5 RN =1+ (P*(N1)=1+(*(51))= CRN = CEIL()=4 FRN = FLOOR()=3 （4 ）* 4800 + ( 3) * 6000 = 5760 SELECT last_name, salary, department_id, PERCENTILE_CONT() 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 Tobias 2800 30 3000 Baida 2900 30 3000 Khoo 3100 30 3000 Raphaely 11000 30 3000 1 Lorentz 4200 60 5760 0 Austin 4800 60 5760 Pataballa 4800 60 5760 Ernst 6000 60 5760 Hunold 9000 60 5760 1 88。PERCENTILE_DISC 功能描述：返回一個(gè)與輸入的分布百分比值相對(duì)應(yīng)的數(shù)據(jù)值，分布百分比的計(jì)算方法見(jiàn)函數(shù)CUME_DIST，如果沒(méi)有正好對(duì)應(yīng)的數(shù)據(jù)值，就取大于該分布值的下一個(gè)值。 注意：本函數(shù)與PERCENTILE_CONT的區(qū)別在找不到對(duì)應(yīng)的分布值時(shí)返回的替代值的計(jì)算方法不同 SAMPLE：， SELECT last_name, salary, department_id, PERCENTILE_DISC() 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 89。RANK 功能描述：根據(jù)ORDER BY子句中表達(dá)式的值，從查詢(xún)返回的每一行，計(jì)算它們與其它行的相對(duì)位置。組內(nèi)的數(shù)據(jù)按ORDER BY子句排序， 然后給每一行賦一個(gè)號(hào)，從而形成一個(gè)序列，該序列從1開(kāi)始，往后累加。每次ORDER BY表達(dá)式的值發(fā)生變化時(shí)，該序列也隨之增加。 有同樣值的行得到同樣的數(shù)字序號(hào)（認(rèn)為null時(shí)相等的）。然而，如果兩行的確得到同樣的排序，則序數(shù)將隨后跳躍。若兩行序數(shù)為1， 則沒(méi)有序數(shù)2，序列將給組中的下一行分配值3，DENSE_RANK則沒(méi)有任何跳躍。 SAMPLE：下例中計(jì)算每個(gè)員工按部門(mén)分區(qū)再按薪水排序，依次出現(xiàn)的序列號(hào)（注意與DENSE_RANK函數(shù)的區(qū)別） SELECT , , , RANK() OVER (PARTITION BY ORDER BY ) as drank FROM employees e, departments d WHERE = AND IN (39。6039。, 39。9039。)。 DEPARTMENT_ID LAST_NAME SALARY DRANK 60 Lorentz 4200 1 60 Austin 4800 2 60 Pataballa 4800 2 60 Ernst 6000 4 60 Hunold 9000 5 90 Kochhar 17000 1 90 De Haan 17000 1 90 King 24000 390。RATIO_TO_REPORT 功能描述：該函數(shù)計(jì)算expression/(sum(expression))的值，它給出相對(duì)于總數(shù)的百分比，即當(dāng)前行對(duì)sum(expression)的貢獻(xiàn)。 SAMPLE：下例計(jì)算每個(gè)員工的工資占該類(lèi)員工總工資的百分比 SELECT last_name, salary, RATIO_TO_REPORT(salary) OVER () AS rr FROM employees WHERE job_id = 39。PU_CLERK39。 LAST_NAME SALARY RR Khoo 3100 .223021583 Baida 2900 .208633094 Tobias 2800 .201438849 Himuro 2600 .18705036 Colmenares 2500 .179856115 ? 91。REGR_ (Linear Regression) Functions 功能描述：這些線(xiàn)性回歸函數(shù)適合最小二乘法回歸線(xiàn)，有9個(gè)不同的回歸函數(shù)可使用。 REGR_SLOPE：返回斜率，等于COVAR_POP(expr1, expr2) / VAR_POP(expr2) REGR_INTERCEPT：返回回歸線(xiàn)的y截距，等于 AVG(expr1) REGR_SLOPE(expr1, expr2) * AVG(expr2) REGR_COUNT：返回用于填充回歸線(xiàn)的非空數(shù)字對(duì)的數(shù)目 REGR_R2：返回回歸線(xiàn)的決定系數(shù)，計(jì)算式為： If VAR_POP(expr2) = 0 then return NULL If VAR_POP(expr1) = 0 and VAR_POP(expr2) != 0 then return 1 If VAR_POP(expr1) 0 and VAR_POP(expr2 != 0 then return POWER(CORR(expr1,expr),2) REGR_AVGX：計(jì)算回歸線(xiàn)的自變量(expr2)的平均值，去掉了空對(duì)(expr1, expr2)后，等于AVG(expr2) REGR_AVGY：計(jì)算回歸線(xiàn)的應(yīng)變量(expr1)的平均值，去掉了空對(duì)(expr1, expr2)后，等于AVG(expr1) REGR_SXX： 返回值等于REGR_COUNT(expr1, expr2) * VAR_POP(expr2) REGR_SYY： 返回值等于REGR_COUNT(expr1, expr2) * VAR_POP(expr1) REGR_SXY: 返回值等于REGR_COUNT(expr1, expr2) * COVAR_POP(expr1, expr2) （下面的例子都是在SH用戶(hù)下完成的） SAMPLE 1：下例計(jì)算1998年最后三個(gè)星期中兩種產(chǎn)品（260和270）在周末的銷(xiāo)售量中已開(kāi)發(fā)票數(shù)量和總數(shù)量的累積斜率和回歸線(xiàn)的截距 SELECT Month, Day, REGR_SLOPE(, ) OVER (ORDER BY , ) AS CUM_SLOPE, REGR_INTERCEPT(, ) OVER (ORDER BY , ) AS CUM_ICPT FROM sales s, times t WHERE = AND IN (270, 260) AND =1998 AND IN (50, 51, 52) AND IN (6,7) ORDER BY , 。 Month Day CUM_SLOPE CUM_ICPT 12 12 68 1872 12 12 68 1872 12 13 12 13 12 19 1287 12 20 12 20 12 20 12 20 12 26 12 26 12 27 12 27 12 27 SAMPLE 2：下例計(jì)算1998年4月每天的累積交易數(shù)量 SELECT UNIQUE , REGR_COUNT(, ) OVER (PARTITION BY ORDER BY ) Regr_Count FROM sales s, times t WHERE = AND = 1998 AND = 4。 DAY_NUMBER_IN_MONTH Regr_Count 1 825 2 1650 3 2475 4 330026 21450 30 22200 SAMPLE 3：下例計(jì)算1998年每月銷(xiāo)售量中已開(kāi)發(fā)票數(shù)量和總數(shù)量的累積回歸線(xiàn)決定系數(shù) SELECT , REGR_R2(SUM(), SUM()) OVER (ORDER BY ) Regr_R2 FROM sales s, times t WHERE = AND = 1998 GROUP BY ORDER BY 。 FISCAL_MONTH_NUMBER Regr_R2 1 2 1 3 .927372984 4 .80701