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;SQL> select ascii('A') A,ascii('a') a,ascii('0') zero,ascii(' ') space from dual;
A A ZERO SPACE--------- --------- --------- ---------65 97 48 32
2.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
3.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
4.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 .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('HELOVEYOU','HE','I')------------------------------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--------weatherwether
14.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)----------------1
21.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)------------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------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 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
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)-----------1182.5032
SQL> 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 nt(*)>=5;
DEPTNO COUNT(*) SUM(SAL)--------- --------- ---------20 5 1087530 6 9400SQL> select deptno,count(*),sum(sal) from scott.emp having count(*)>=5 group by tno ;
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
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