ASCII
返回与指定的字符对应的十进制数;SQL> select ascii(A) A,ascii(a) a,ascii(0) zero,ascii( ) space from dual;A A ZERO SPACE
65 97 48 32
CHR
给出整数,返回对应的字符;SQL> select chr(54740) zhao,chr(65) chr65 from dual;ZH C
赵 A
CONCAT
连接两个字符串;SQL> select concat(010-,88888888)||转23 高乾竞电话 from dual;
高乾竞电话
010-88888888转23
INITCAP
返回字符串并将字符串的第一个字母变为大写;SQL> select initcap(smith) upp from dual;
UPP
Smith
5.INSTR(C1,C2,I,J)在一个字符串中搜索指定的字符,返回发现指定的字符的位置;C1 被搜索的字符串C2 希望搜索的字符串I 搜索的开始位置,默认为1J 出现的位置,默认为1SQL> select instr(oracle traning,ra,1,2) instring from dual;
INSTRING
9
6.LENGTH返回字符串的长度;SQL> select name,length(name),addr,length(addr),sal,length(to_char(sal)) from gao.nchar_tst;NAME LENGTH(NAME) ADDR LENGTH(ADDR) SAL LENGTH(TO_CHAR(SAL))
高乾竞 3 北京市海锭区 6 9999.99 7
7.LOWER返回字符串,并将所有的字符小写SQL> select lower(AaBbCcDd)AaBbCcDd from dual;
AABBCCDD
aabbccdd
8.UPPER返回字符串,并将所有的字符大写SQL> select upper(AaBbCcDd) upper from dual;
UPPER
AABBCCDD
9.RPAD和LPAD(粘贴字符)RPAD 在列的右边粘贴字符LPAD 在列的左边粘贴字符SQL> select lpad(rpad(gao,10,),17,)from dual;
LPAD(RPAD(GAO,1
gao不够字符则用*来填满
10.LTRIM和RTRIMLTRIM 删除左边出现的字符串RTRIM 删除右边出现的字符串SQL> select ltrim(rtrim( gao qian jing , ), ) from dual;
LTRIM(RTRIM(
gao qian jing
11.SUBSTR(string,start,count)取子字符串,从start开始,取count个SQL> select substr(13088888888,3,8) from dual;
SUBSTR(
08888888
12.REPLACE(string,s1,s2)string 希望被替换的字符或变量s1 被替换的字符串s2 要替换的字符串SQL> select replace(he love you,he,i) from dual;
REPLACE(H
i love you
13.SOUNDEX返回一个与给定的字符串读音相同的字符串SQL> create table table1(xm varchar(8));SQL> insert into table1 values(weather);SQL> insert into table1 values(wether);SQL> insert into table1 values(gao);SQL> select xm from table1 where soundex(xm)=soundex(weather);
XM
weatherwether14.TRIM(s from string)LEADING 剪掉前面的字符TRAILING 剪掉后面的字符如果不指定,默认为空格符15.ABS返回指定值的绝对值SQL> select abs(100),abs(-100) from dual;ABS(100) ABS(-100)
100 100
16.ACOS给出反余弦的值SQL> select acos(-1) from dual;
ACOS(-1)
3.1415927
17.ASIN给出反正弦的值SQL> select asin(0.5) from dual;
ASIN(0.5)
.52359878
18.ATAN返回一个数字的反正切值SQL> select atan(1) from dual;
ATAN(1)
.78539816
19.CEIL返回大于或等于给出数字的最小整数SQL> select ceil(3.1415927) from dual;
CEIL(3.1415927)
4
20.COS返回一个给定数字的余弦SQL> select cos(-3.1415927) from dual;
COS(-3.1415927)
-121.COSH返回一个数字反余弦值SQL> select cosh(20) from dual;
COSH(20)
242582598
22.EXP返回一个数字e的n次方根SQL> select exp(2),exp(1) from dual;EXP(2) EXP(1)
7.3890561 2.7182818
23.FLOOR对给定的数字取整数SQL> select floor(2345.67) from dual;
FLOOR(2345.67)
2345
24.LN返回一个数字的对数值SQL> select ln(1),ln(2),ln(2.7182818) from dual;LN(1) LN(2) LN(2.7182818)
0 .69314718 .99999999
25.LOG(n1,n2)返回一个以n1为底n2的对数SQL> select log(2,1),log(2,4) from dual;LOG(2,1) LOG(2,4)
0 2
26.MOD(n1,n2)返回一个n1除以n2的余数SQL> select mod(10,3),mod(3,3),mod(2,3) from dual;MOD(10,3) MOD(3,3) MOD(2,3)
1 0 2
27.POWER返回n1的n2次方根SQL> select power(2,10),power(3,3) from dual;POWER(2,10) POWER(3,3)
1024 27
28.ROUND和TRUNC按照指定的精度进行舍入SQL> select round(55.5),round(-55.4),trunc(55.5),trunc(-55.5) from dual;ROUND(55.5) ROUND(-55.4) TRUNC(55.5) TRUNC(-55.5)
56 -55 55 -55
29.SIGN取数字n的符号,大于0返回1,小于0返回-1,等于0返回0SQL> select sign(123),sign(-100),sign(0) from dual;SIGN(123) SIGN(-100) SIGN(0)
1 -1 0
30.SIN返回一个数字的正弦值SQL> select sin(1.57079) from dual;
SIN(1.57079)
131.SIGH返回双曲正弦的值SQL> select sin(20),sinh(20) from dual;SIN(20) SINH(20)
.91294525 242582598
32.SQRT返回数字n的根SQL> select sqrt(64),sqrt(10) from dual;SQRT(64) SQRT(10)
8 3.1622777
33.TAN返回数字的正切值SQL> select tan(20),tan(10) from dual;TAN(20) TAN(10)
2.2371609 .64836083
34.TANH返回数字n的双曲正切值SQL> select tanh(20),tan(20) from dual;TANH(20) TAN(20)
1 2.2371609
35.TRUNC按照指定的精度截取一个数SQL> select trunc(124.1666,-2) trunc1,trunc(124.16666,2) from dual;TRUNC1 TRUNC(124.16666,2)
100 124.16
36.ADD_MONTHS增加或减去月份SQL> select to_char(add_months(to_date(199912,yyyymm),2),yyyymm) from dual;
TO_CHA
200002SQL> select to_char(add_months(to_date(199912,yyyymm),-2),yyyymm) from dual;
TO_CHA
199910
37.LAST_DAY返回日期的最后一天SQL> select to_char(sysdate,yyyy.mm.dd),to_char((sysdate)+1,yyyy.mm.dd) from dual;TO_CHAR(SY TO_CHAR((S
2004.05.09 2004.05.10SQL> select last_day(sysdate) from dual;
LAST_DAY(S
31-5月 -04
38.MONTHS_BETWEEN(date2,date1)给出date2-date1的月份SQL> select months_between(19-12月-1999,19-3月-1999) mon_between from dual;
MON_BETWEEN
9SQL>selectmonths_between(to_date(2000.05.20,yyyy.mm.dd),to_date(2005.05.20,yyyy.mm.dd)) mon_betw from dual;
MON_BETW
-60
39.NEW_TIME(date,this,that)给出在this时区=other时区的日期和时间SQL> select to_char(sysdate,yyyy.mm.dd hh24:mi:ss) bj_time,to_char(new_time2 (sysdate,PDT,GMT),yyyy.mm.dd hh24:mi:ss) los_angles from dual;BJ_TIME LOS_ANGLES
2004.05.09 11:05:32 2004.05.09 18:05:32
40.NEXT_DAY(date,day)给出日期date和星期x之后计算下一个星期的日期SQL> select next_day('18-5月-2001','星期五') next_day from dual;
NEXT_DAY
25-5月 -01
41.SYSDATE用来得到系统的当前日期SQL> select to_char(sysdate,dd-mm-yyyy day) from dual;
TO_CHAR(SYSDATE,
09-05-2004 星期日trunc(date,fmt)按照给出的要求将日期截断,如果fmt=mi表示保留分,截断秒SQL> select to_char(trunc(sysdate,hh),yyyy.mm.dd hh24:mi:ss) hh,2 to_char(trunc(sysdate,mi),yyyy.mm.dd hh24:mi:ss) hhmm from dual;HH HHMM
2004.05.09 11:00:00 2004.05.09 11:17:00
42.CHARTOROWID将字符数据类型转换为ROWID类型SQL> select rowid,rowidtochar(rowid),ename from scott.emp;ROWID ROWIDTOCHAR(ROWID) ENAME
AAAAfKAACAAAAEqAAA AAAAfKAACAAAAEqAAA SMITHAAAAfKAACAAAAEqAAB AAAAfKAACAAAAEqAAB ALLENAAAAfKAACAAAAEqAAC AAAAfKAACAAAAEqAAC WARDAAAAfKAACAAAAEqAAD AAAAfKAACAAAAEqAAD JONES
43.CONVERT(c,dset,sset)将源字符串 sset从一个语言字符集转换到另一个目的dset字符集SQL> select convert(strutz,we8hp,f7dec) "conversion" from dual;
conver
strutz
44.HEXTORAW将一个十六进制构成的字符串转换为二进制
45.RAWTOHEXT将一个二进制构成的字符串转换为十六进制
46.ROWIDTOCHAR将ROWID数据类型转换为字符类型
47.TO_CHAR(date,format)SQL> select to_char(sysdate,yyyy/mm/dd hh24:mi:ss) from dual;
TO_CHAR(SYSDATE,YY
2004/05/09 21:14:4148.TO_DATE(string,format)将字符串转化为ORACLE中的一个日期
49.TO_MULTI_BYTE将字符串中的单字节字符转化为多字节字符SQL> select to_multi_byte(高) from dual;
TO
高
50.TO_NUMBER将给出的字符转换为数字SQL> select to_number(1999) year from dual;
YEAR
199951.BFILENAME(dir,file)指定一个外部二进制文件SQL>insert into file_tb1 values(bfilename(lob_dir1,image1.gif));
52.CONVERT(x,desc,source)将x字段或变量的源source转换为descSQL> select sid,serial#,username,decode(command,2 0,none,3 2,insert,4 3,5 select,6 6,update,7 7,delete,8 8,drop,9 other) cmd from v$session where type!=background;SID SERIAL# USERNAME CMD
1 1 none2 1 none3 1 none4 1 none5 1 none6 1 none7 1275 none8 1275 none9 20 GAO select10 40 GAO none
53.DUMP(s,fmt,start,length)DUMP函数以fmt指定的内部数字格式返回一个VARCHAR2类型的值SQL> col global_name for a30SQL> col dump_string for a50SQL> set lin 200SQL> select global_name,dump(global_name,1017,8,5) dump_string from global_name;GLOBAL_NAME DUMP_STRING
ORACLE.WORLD Typ=1 Len=12 CharacterSet=ZHS16GBK: W,O,R,L,D
54.EMPTY_BLOB()和EMPTY_CLOB()这两个函数都是用来对大数据类型字段进行QQ号码交易初始化操作的函数
55.GREATEST返回一组表达式中的最大值,即比较字符的编码大小.SQL> select greatest(AA,AB,AC) from dual;
GR
ACSQL> select greatest(啊,安,天) from dual;
GR
天
56.LEAST返回一组表达式中的最小值SQL> select least(啊,安,天) from dual;
LE
啊
57.UID返回标识当前用户的唯一整数SQL> show userUSER 为"GAO"SQL> select username,user_id from dba_users where user_id=uid;USERNAME USER_ID
GAO 25
58.USER返回当前用户的名字SQL> select user from dual;
USER
GAO
59.USEREVN返回当前用户环境的信息,opt可以是:ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZEISDBA 查看当前用户是否是DBA如果是则返回trueSQL> select userenv(isdba) from dual;
USEREN
FALSESQL> select userenv(isdba) from dual;
USEREN
TRUESESSION返回会话标志SQL> select userenv(sessionid) from dual;
USERENV(SESSIONID)
152ENTRYID返回会话人口标志SQL> select userenv(entryid) from dual;
USERENV(ENTRYID)
INSTANCE返回当前INSTANCE的标志SQL> select userenv(instance) from dual;
USERENV(INSTANCE)
1LANGUAGE返回当前环境变量SQL> select userenv(language) from dual;
USERENV(LANGUAGE)
SIMPLIFIED CHINESE_CHINA.ZHS16GBKLANG返回当前环境的语言的缩写SQL> select userenv(lang) from dual;
USERENV(LANG)
ZHSTERMINAL返回用户的终端或机器的标志SQL> select userenv(terminal) from dual;
USERENV(TERMINA
GAOVSIZE(X)返回X的大小(字节)数SQL> select vsize(user),user from dual;VSIZE(USER) USER
6 SYSTEM60.AVG(DISTINCT|ALL)all表示对所有的值求平均值,distinct只对不同的值求平均值SQLWKS> create table table3(xm varchar(8),sal number(7,2));语句已处理。SQLWKS> insert into table3 values(gao,1111.11);SQLWKS> insert into table3 values(gao,1111.11);SQLWKS> insert into table3 values(zhu,5555.55);SQLWKS> commit;SQL> select avg(distinct sal) from gao.table3;
AVG(DISTINCTSAL)
3333.33SQL> select avg(all sal) from gao.table3;
AVG(ALLSAL)
2592.59
61.MAX(DISTINCT|ALL)求最大值,ALL表示对所有的值求最大值,DISTINCT表示对不同的值求最大值,相同的只取一次SQL> select max(distinct sal) from scott.emp;
MAX(DISTINCTSAL)
5000
62.MIN(DISTINCT|ALL)求最小值,ALL表示对所有的值求最小值,DISTINCT表示对不同的值求最小值,相同的只取一次SQL> select min(all sal) from gao.table3;
MIN(ALLSAL)
1111.11
63.STDDEV(distinct|all)求标准差,ALL表示对所有的值求标准差,DISTINCT表示只对不同的值求标准差SQL> select stddev(sal) from scott.emp;
STDDEV(SAL)
1182.5032SQL> select stddev(distinct sal) from scott.emp;
STDDEV(DISTINCTSAL)
1229.951
64.VARIANCE(DISTINCT|ALL)求协方差SQL> select variance(sal) from scott.emp;
VARIANCE(SAL)
1398313.9
65.GROUP BY主要用来对一组数进行统计SQL> select deptno,count(*),sum(sal) from scott.emp group by deptno;DEPTNO COUNT(*) SUM(SAL)
10 3 875020 5 1087530 6 9400
66.HAVING对分组统计再加限制条件SQL> select deptno,count(),sum(sal) from scott.emp group by deptno having count()>=5;DEPTNO COUNT(*) SUM(SAL)
20 5 1087530 6 9400SQL> select deptno,count(),sum(sal) from scott.emp having count()>=5 group by deptno ;DEPTNO COUNT(*) SUM(SAL)
20 5 1087530 6 9400
67.ORDER BY用于对查询到的结果进行排序输出SQL> select deptno,ename,sal from scott.emp order by deptno,sal desc;DEPTNO ENAME SAL
10 KING 500010 CLARK 245010 MILLER 130020 SCOTT 300020 FORD 300020 JONES 297520 ADAMS 110020 SMITH 80030 BLAKE 285030 ALLEN 160030 TURNER 150030 WARD 125030 MARTIN 125030 JAMES 950
pl/sql中的case语句
select (case when DUMMY='X' then 0 else 1 end) as flag from dual;case的第1种用法：case col when 'a' then 1when 'b' then 2else 0 end这种用法跟decode一样没什么区别case的第2种用法：case when score <60 then 'd'when score >=60 and score <70 then 'c'when score >=70 and score <80 then 'b'else 'a' end69.NVL(expr1, expr2)NVL(expr1, expr2)->expr1为NULL，返回expr2；不为NULL，返回expr1。注意两者的类型要一致NVL2 (expr1, expr2, expr3) ->expr1不为NULL，返回expr2；为NULL，返回expr3。expr2和expr3类型不同的话，expr3会转换为expr2的类型NULLIF (expr1, expr2) ->相等返回NULL，不等返回expr1
Oracle分析函数参考手册
作者: xsb(http://xsb.itpub.net)发表于:2006.03.01 12:22
分类: DW&BI
Oracle从8.1.6开始提供分析函数，分析函数用于计算基于组的某种聚合值，它和聚合函数的不同之处是对于每个组返回多行，而聚合函数对于每个组只返回一行。常用的分析函数如下所列:row_number() over(partition by ... order by ...)rank() over(partition by ... order by ...)dense_rank() over(partition by ... order by ...)count() over(partition by ... order by ...)max() over(partition by ... order by ...)min() over(partition by ... order by ...)sum() over(partition by ... order by ...)avg() over(partition by ... order by ...)first_value() over(partition by ... order by ...)last_value() over(partition by ... order by ...)lag() over(partition by ... order by ...)lead() over(partition by ... order by ...)
下面例子中使用的表来自Oracle自带的HR用户下的表，如果没有安装该用户，可以在SYS用户下运行$ORACLE_HOME/demo/schema/human_resources/hr_main.sql来创建。
本文如果未指明，缺省是在HR用户下运行例子。开窗函数的的理解：开窗函数指定了分析函数工作的数据窗口大小，这个数据窗口大小可能会随着行的变化而变化，举例如下：over（order by salary） 按照salary排序进行累计，order by是个默认的开窗函数over（partition by deptno）按照部门分区over（order by salary range between 50 preceding and 150 following）每行对应的数据窗口是之前行幅度值不超过50，之后行幅度值不超过150over（order by salary rows between 50 preceding and 150 following）每行对应的数据窗口是之前50行，之后150行over（order by salary rows between unbounded preceding and unbounded following）每行对应的数据窗口是从第一行到最后一行，等效：over（order by salary range between unbounded preceding and unbounded following）主要参考资料：《expert one-on-one》 Tom Kyte 《Oracle9i SQL Reference》第6章ohwww 2007-3-12 09:19
续70。AVG功能描述：用于计算一个组和数据窗口内表达式的平均值。SAMPLE：下面的例子中列c_mavg计算员工表中每个员工的平均薪水报告，该平均值由当前员工和与之具有相同经理的前一个和后一个三者的平均数得来；SELECT manager_id, last_name, hire_date, salary,AVG(salary) OVER (PARTITION BY manager_id ORDER BY hire_dateROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING) AS c_mavgFROM employees;MANAGER_ID LAST_NAME HIRE_DATE SALARY C_MAVG
100 Kochhar 21-SEP-89 17000 17000100 De Haan 13-JAN-93 17000 15000100 Raphaely 07-DEC-94 11000 11966.6667100 Kaufling 01-MAY-95 7900 10633.3333100 Hartstein 17-FEB-96 13000 9633.33333100 Weiss 18-JUL-96 8000 11666.6667100 Russell 01-OCT-96 14000 11833.333371。CORR功能描述：返回一对表达式的相关系数，它是如下的缩写：COVAR_POP(expr1,expr2)/STDDEV_POP(expr1)*STDDEV_POP(expr2))从统计上讲，相关性是变量之间关联的强度，变量之间的关联意味着在某种程度上一个变量的值可由其它的值进行预测。通过返回一个-1~1之间的一个数, 相关系数给出了关联的强度，0表示不相关。SAMPLE：下例返回1998年月销售收入和月单位销售的关系的累积系数（本例在SH用户下运行）SELECT t.calendar_month_number,CORR (SUM(s.amount_sold), SUM(s.quantity_sold))OVER (ORDER BY t.calendar_month_number) as CUM_CORRFROM sales s, times tWHERE s.time_id = t.time_id AND calendar_year = 1998GROUP BY t.calendar_month_numberORDER BY t.calendar_month_number;CALENDAR_MONTH_NUMBER CUM_CORR
12 13 .9943093824 .8520408755 .8466522046 .8712506287 .9100298038 .9175563999 .92015435610 .8672025111 .84486476512 .903542662
72。COVAR_POP功能描述：返回一对表达式的总体协方差。SAMPLE：下例CUM_COVP返回定价和最小产品价格的累积总体协方差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_COVSFROM product_information pWHERE category_id = 29ORDER BY product_id, supplier_id;PRODUCT_ID SUPPLIER_ID CUM_COVP CUM_COVS
1774 103088 01775 103087 1473.25 2946.51794 103096 1702.77778 2554.166671825 103093 1926.25 2568.333332004 103086 1591.4 1989.252005 103086 1512.5 18152416 103088 1475.97959 1721.97619..
73。COVAR_SAMP功能描述：返回一对表达式的样本协方差SAMPLE：下例CUM_COVS返回定价和最小产品价格的累积样本协方差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_COVSFROM product_information pWHERE category_id = 29ORDER BY product_id, supplier_id;PRODUCT_ID SUPPLIER_ID CUM_COVP CUM_COVS
1774 103088 01775 103087 1473.25 2946.51794 103096 1702.77778 2554.166671825 103093 1926.25 2568.333332004 103086 1591.4 1989.252005 103086 1512.5 18152416 103088 1475.97959 1721.9761974。COUNT功能描述：对一组内发生的事情进行累积计数，如果指定*或一些非空常数，count将对所有行计数，如果指定一个表达式，count返回表达式非空赋值的计数，当有相同值出现时，这些相等的值都会被纳入被计算的值；可以使用DISTINCT来记录去掉一组中完全相同的数据后出现的行数。SAMPLE：下面例子中计算每个员工在按薪水排序中当前行附近薪水在[n-50,n+150]之间的行数，n表示当前行的薪水例如，Philtanker的薪水2200，排在他之前的行中薪水大于等于2200-50的有1行，排在他之后的行中薪水小于等于2200＋150的行没有，所以count计数值cnt3为2（包括自己当前行）；cnt2值相当于小于等于当前行的SALARY值的所有行数SELECT last_name, salary, COUNT(*) OVER () AS cnt1,COUNT(*) OVER (ORDER BY salary) AS cnt2,COUNT(*) OVER (ORDER BY salary RANGE BETWEEN 50 PRECEDINGAND 150 FOLLOWING) AS cnt3 FROM employees;LAST_NAME SALARY CNT1 CNT2 CNT3
Olson 2100 107 1 3Markle 2200 107 3 2Philtanker 2200 107 3 2Landry 2400 107 5 8Gee 2400 107 5 8Colmenares 2500 107 11 10Patel 2500 107 11 10..75。CUME_DIST功能描述：计算一行在组中的相对位置，CUME_DIST总是返回大于0、小于或等于1的数，该数表示该行在N行中的位置。例如，在一个3行的组中，返回的累计分布值为1/3、2/3、3/3SAMPLE：下例中计算每个工种的员工按薪水排序依次累积出现的分布百分比SELECT job_id, last_name, salary, CUME_DIST()OVER (PARTITION BY job_id ORDER BY salary) AS cume_distFROM employees WHERE job_id LIKE 'PU%';JOB_ID LAST_NAME SALARY CUME_DIST
PU_CLERK Colmenares 2500 .2PU_CLERK Himuro 2600 .4PU_CLERK Tobias 2800 .6PU_CLERK Baida 2900 .8PU_CLERK Khoo 3100 1PU_MAN Raphaely 11000 176。DENSE_RANK功能描述：根据ORDER BY子句中表达式的值，从查询返回的每一行，计算它们与其它行的相对位置。组内的数据按ORDER BY子句排序，然后给每一行赋一个号，从而形成一个序列，该序列从1开始，往后累加。每次ORDER BY表达式的值发生变化时，该序列也随之增加。有同样值的行得到同样的数字序号（认为null时相等的）。密集的序列返回的时没有间隔的数SAMPLE：下例中计算每个员工按部门分区再按薪水排序，依次出现的序列号（注意与RANK函数的区别）SELECT d.department_id , e.last_name, e.salary, DENSE_RANK()OVER (PARTITION BY e.department_id ORDER BY e.salary) as drankFROM employees e, departments dWHERE e.department_id = d.department_idAND d.department_id IN ('60', '90');DEPARTMENT_ID LAST_NAME SALARY DRANK
60 Lorentz 4200 160 Austin 4800 260 Pataballa 4800 260 Ernst 6000 360 Hunold 9000 490 Kochhar 17000 190 De Haan 17000 190 King 24000 2
77。FIRST功能描述：从DENSE_RANK返回的集合中取出排在最前面的一个值的行（可能多行，因为值可能相等），因此完整的语法需要在开始处加上一个集合函数以从中取出记录SAMPLE：下面例子中DENSE_RANK按部门分区，再按佣金commission_pct排序，FIRST取出佣金最低的对应的所有行，然后前面的MAX函数从这个集合中取出薪水最低的值；LAST取出佣金最高的对应的所有行，然后前面的MIN函数从这个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 employeesWHERE department_id in (20,80)ORDER BY department_id, salary;LAST_NAME DEPARTMENT_ID SALARY Worst Best
Fay 20 6000 6000 13000Hartstein 20 13000 6000 13000Kumar 80 6100 6100 14000Banda 80 6200 6100 14000Johnson 80 6200 6100 14000Ande 80 6400 6100 14000Lee 80 6800 6100 14000Tuvault 80 7000 6100 14000Sewall 80 7000 6100 14000Marvins 80 7200 6100 14000Bates 80 7300 6100 14000...78。FIRST_VALUE功能描述：返回组中数据窗口的第一个值。SAMPLE：下面例子计算按部门分区按薪水排序的数据窗口的第一个值对应的名字，如果薪水的第一个值有多个，则从多个对应的名字中取缺省排序的第一个名字SELECT department_id, last_name, salary, FIRST_VALUE(last_name)OVER (PARTITION BY department_id ORDER BY salary ASC ) AS lowest_salFROM employeesWHERE department_id in(20,30);DEPARTMENT_ID LAST_NAME SALARY LOWEST_SAL
20 Fay 6000 Fay20 Hartstein 13000 Fay30 Colmenares 2500 Colmenares30 Himuro 2600 Colmenares30 Tobias 2800 Colmenares30 Baida 2900 Colmenares30 Khoo 3100 Colmenares30 Raphaely 11000 Colmenares
79。LAG功能描述：可以访问结果集中的其它行而不用进行自连接。它允许去处理游标，就好像游标是一个数组一样。在给定组中可参考当前行之前的行，这样就可以从组中与当前行一起选择以前的行。Offset是一个正整数，其默认值为1，若索引超出窗口的范围，就返回默认值（默认返回的是组中第一行），其相反的函数是LEADSAMPLE：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_salFROM employeesWHERE job_id = 'PU_CLERK';LAST_NAME HIRE_DATE SALARY PREV_SAL
Khoo 18-5月 -95 3100 0Tobias 24-7月 -97 2800 3100Baida 24-12月-97 2900 2800Himuro 15-11月-98 2600 2900Colmenares 10-8月 -99 2500 2600