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SQL中的单记录函数1.ASCII返回与指定的字符对应的十进制数;SQLselectascii('A')A,ascii('a')a,ascii('0')zero,ascii('')spacefromdual;AAZEROSPACE------------------------------------659748322.CHR给出整数,返回对应的字符;SQLselectchr(54740)zhao,chr(65)chr65fromdual;ZHC---赵A3.CONCAT连接两个字符串;SQLselectconcat('010-','88888888')||'转23'高乾竞电话fromdual;高乾竞电话----------------010-88888888转234.INITCAP返回字符串并将字符串的第一个字母变为大写;SQLselectinitcap('smith')uppfromdual;UPP-----Smith5.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1SQLselectinstr('oracletraning','ra',1,2)instringfromdual;INSTRING---------96.LENGTH返回字符串的长度;SQLselectname,length(name),addr,length(addr),sal,length(to_char(sal))from.nchar_tst;NAMELENGTH(NAME)ADDRLENGTH(ADDR)SALLENGTH(TO_CHAR(SAL))---------------------------------------------------------------------------高乾竞3北京市海锭区69999.9977.LOWER返回字符串,并将所有的字符小写SQLselectlower('AaBbCcDd')AaBbCcDdfromdual;AABBCCDD--------aabbccdd8.UPPER返回字符串,并将所有的字符大写SQLselectupper('AaBbCcDd')upperfromdual;UPPER--------AABBCCDD9.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SQLselectlpad(rpad('gao',10,'*'),17,'*')fromdual;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SQLselectltrim(rtrim('gaoqianjing',''),'')fromdual;LTRIM(RTRIM('-------------gaoqianjing11.SUBSTR(string,start,count)取子字符串,从start开始,取count个SQLselectsubstr('13088888888',3,8)fromdual;SUBSTR('--------0888888812.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SQLselectreplace('heloveyou','he','i')fromdual;REPLACE('HELOVEYOU','HE','I')------------------------------iloveyou13.SOUNDEX返回一个与给定的字符串读音相同的字符串SQLcreatetabletable1(xmvarchar(8));SQLinsertintotable1values('weather');SQLinsertintotable1values('wether');SQLinsertintotable1values('gao');SQLselectxmfromtable1wheresoundex(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SQLselectabs(100),abs(-100)fromdual;ABS(100)ABS(-100)------------------10010016.ACOS给出反余弦的值SQLselectacos(-1)fromdual;ACOS(-1)---------3.141592717.ASIN给出反正弦的值SQLselectasin(0.5)fromdual;ASIN(0.5)---------.5235987818.ATAN返回一个数字的反正切值SQLselectatan(1)fromdual;ATAN(1)---------.7853981619.CEIL返回大于或等于给出数字的最小整数SQLselectceil(3.1415927)fromdual;CEIL(3.1415927)---------------420.COS返回一个给定数字的余弦SQLselectcos(-3.1415927)fromdual;COS(-3.1415927)----------------121.COSH返回一个数字反余弦值SQLselectcosh(20)fromdual;COSH(20)---------24258259822.EXP返回一个数字e的n次方根SQLselectexp(2),exp(1)fromdual;EXP(2)EXP(1)------------------7.38905612.718281823.FLOOR对给定的数字取整数SQLselectfloor(2345.67)fromdual;FLOOR(2345.67)--------------234524.LN返回一个数字的对数值SQLselectln(1),ln(2),ln(2.7182818)fromdual;LN(1)LN(2)LN(2.7182818)-------------------------------0.69314718.9999999925.LOG(n1,n2)返回一个以n1为底n2的对数SQLselectlog(2,1),log(2,4)fromdual;LOG(2,1)LOG(2,4)------------------0226.MOD(n1,n2)返回一个n1除以n2的余数SQLselectmod(10,3),mod(3,3),mod(2,3)fromdual;MOD(10,3)MOD(3,3)MOD(2,3)---------------------------10227.POWER返回n1的n2次方根SQLselectpower(2,10),power(3,3)fromdual;POWER(2,10)POWER(3,3)---------------------10242728.ROUND和TRUNC按照指定的精度进行舍入SQLselectround(55.5),round(-55.4),trunc(55.5),trunc(-55.5)fromdual;ROUND(55.5)ROUND(-55.4)TRUNC(55.5)TRUNC(-55.5)----------------------------------------------56-5555-5529.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0SQLselectsign(123),sign(-100),sign(0)fromdual;SIGN(123)SIGN(-100)SIGN(0)----------------------------1-1030.SIN返回一个数字的正弦值SQLselectsin(1.57079)fromdual;SIN(1.57079)------------131.SIGH返回双曲正弦的值SQLselectsin(20),sinh(20)fromdual;SIN(20)SINH(20)------------------.9129452524258259832.SQRT返回数字n的根SQLselectsqrt(64),sqrt(10)fromdual;SQRT(64)SQRT(10)------------------83.162277733.TAN返回数字的正切值SQLselecttan(20),tan(10)fromdual;TAN(20)TAN(10)------------------2.2371609.6483608334.TANH返回数字n的双曲正切值SQLselecttanh(20),tan(20)fromdual;TANH(20)TAN(20)------------------12.237160935.TRUNC按照指定的精度截取一个数SQLselecttrunc(124.1666,-2)trunc1,trunc(124.16666,2)fromdual;TRUNC1TRUNC(124.16666,2)---------------------------100124.1636.ADD_MONTHS增加或减去月份SQLselectto_char(add_months(to_date('199912','yyyymm'),2),'yyyymm')fromdual;TO_CHA------200002SQLselectto_char(add_months(to_date('199912','yyyymm'),-2),'yyyymm')fromdual;TO_CHA------19991037.LAST_DAY返回日期的最后一天SQLselectto_char(sysdate,'yyyy.mm.dd'),to_char((sysdate)+1,'yyyy.mm.dd')fromdual;TO_CHAR(SYTO_CHAR((S--------------------2004.05.092004.05.10SQLselectlast_day(sysdate)fromdual;LAST_DAY(S----------31-5月-0438.MONTHS_BETWEEN(date2,date1)给出date2-date1的月份SQLselectmonths_between('19-12月-1999','19-3月-1999')mon_betweenfromdual;MON_BETWEEN-----------9SQLselectmonths_between(to_date('2000.05.20','yyyy.mm.dd'),to_date('2005.05.20','yyyy.dd'))mon_betwfromdual;MON_BETW----------6039.NEW_TIME(date,'this','that')给出在this时区=other时区的日期和时间SQLselectto_char(sysdate,'yyyy.mm.ddhh24:mi:ss')bj_time,to_char(new_time2(sysdate,'PDT','GMT'),'yyyy.mm.ddhh24:mi:ss')los_anglesfromdual;BJ_TIMELOS_ANGLES--------------------------------------2004.0