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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0 SQL> 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) ------------ 1 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 ------ 200002 SQL> 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 2004.05.10 SQL> 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 ----------- 9 SQL>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_time 2 (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 SMITH AAAAfKAACAAAAEqAAB AAAAfKAACAAAAEqAAB ALLEN AAAAfKAACAAAAEqAAC AAAAfKAACAAAAEqAAC WARD AAAAfKAACAAAAEqAAD 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desc SQL> 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 a30 SQL> col dump_string for a50 SQL> set lin 200 SQL> 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 -- AC SQL> 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 user USER 为"GAO" SQL> select username,user_id from dba_users where user_id=uid; USERNAME USER_ID ------------------------------ --------- (责任编辑：admin) |