31.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.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 21:14:41
48.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--------- 1999
51.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 none 2 1 none 3 1 none 4 1 none 5 1 none 6 1 none 7 1275 none 8 1275 none 9 20 GAO select 10 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')------------------ 0INSTANCE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 SYSTEM
60.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)---------------- 3333.33
SQL> select avg(all sal) from gao.table3;
AVG(ALLSAL)----------- 2592.59
