1.ASCII返回与指定的字符对应的十进制数;SQL>selectascii(A)A,ascii(a)a,ascii(0)zero,ascii()spacefromdual;AAZEROSPACE------------------------------------65974832CHR给出整数,返回对应的字符;SQL>selectchr(54740)zhao,chr(65)chr65fromdual;ZHC---赵A2.CONCAT连接两个字符串;SQL>selectconcat(010-,88888888)||转23高乾竞电话fromdual;高乾竞电话----------------010-88888888转233.WM_CONCAT实现字符集选，wm_concat(colum)是把column这一列合并到一行，默认以','隔开。replace(wm_concat(column),',','+')则是在合并的同时，用'+'取代原来默认的','4.CAST类型转换，针对的是Oracle的数据类型。Selectcast(aasint)fromt1Selectcast(aasnumber(8,4))fromt15.INITCAP返回字符串并将字符串的第一个字母变为大写;SQL>selectinitcap(smith)uppfromdual;UPP-----SmithINSTR(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>selectinstr(oracletraning,ra,1,2)instringfromdual;INSTRING---------9LENGTH返回字符串的长度;SQL>selectname,length(name),addr,length(addr),sal,length(to_char(sal))fromgao.nchar_tst;NAMELENGTH(NAME)ADDRLENGTH(ADDR)SALLENGTH(TO_CHAR(SAL))---------------------------------------------------------------------------高乾竞3北京市海锭区69999.997LOWER返回字符串,并将所有的字符小写SQL>selectlower(AaBbCcDd)AaBbCcDdfromdual;AABBCCDD--------aabbccddUPPER返回字符串,并将所有的字符大写SQL>selectupper(AaBbCcDd)upperfromdual;UPPER--------AABBCCDDRPAD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>selectlpad(rpad(gao,10,*),17,*)fromdual;LPAD(RPAD(GAO,1-----------------*******gao*******不够字符则用*来填满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>selectltrim(rtrim(gaoqianjing,),)fromdual;LTRIM(RTRIM(-------------gaoqianjingSUBSTR(string,start,count)取子字符串,从start开始,取count个SQL>selectsubstr(13088888888,3,8)fromdual;SUBSTR(--------08888888REPLACE(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>selectreplace(heloveyou,he,i)fromdual;REPLACE(H----------iloveyouSOUNDEX返回一个与给定的字符串读音相同的字符串SQL>createtabletable1(xmvarchar(8));SQL>insertintotable1values(weather);SQL>insertintotable1values(wether);SQL>insertintotable1values(gao);SQL>selectxmfromtable1wheresoundex(xm)=soundex(weather);XM--------weatherwether6.TRIM(sfromstring)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ABS返回指定值的绝对值SQL>selectabs(100),abs(-100)fromdual;ABS(100)ABS(-100)------------------100100ACOS给出反余弦的值SQL>selectacos(-1)fromdual;ACOS(-1)---------3.1415927ASIN给出反正弦的值SQL>selectasin(0.5)fromdual;ASIN(0.5)---------.52359878ATAN返回一个数字的反正切值SQL>selectatan(1)fromdual;ATAN(1)---------.78539816CEIL返回大于或等于给出数字的最小整数SQL>selectceil(3.1415927)fromdual;CEIL(3.1415927)---------------4COS返回一个给定数字的余弦SQL>selectcos(-3.1415927)fromdual;COS(-3.1415927)----------------17.COSH返回一个数字反余弦值SQL>selectcosh(20)fromdual;COSH(20)---------242582598EXP返回一个数字e的n次方根SQL>selectexp(2),exp(1)fromdual;EXP(2)EXP(1)------------------7.38905612.7182818FLOOR对给定的数字取整数SQL>selectfloor(2345.67)fromdual;FLOOR(2345.67)--------------2345LN返回一个数字的对数值SQL>selectln(1),ln(2),ln(2.7182818)fromdual;LN(1)LN(2)LN(2.7182818)-------------------------------0.69314718.99999999LOG(n1,n2)返回一个以n1为底n2的对数SQL>selectlog(2,1),log(2,4)fromdual;...
