SQL中的单历史记录表达式1.ASCII回到与选定的字符串相关联的进制数;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得出有理数,回到相关联的字符串;SQL> select chr(54740) zhao,chr(65) chr65 from dual;
ZH C-- -赵 A
3.CONCAT相连三个数组;SQL> select concat(010-,88888888)||转23 高乾竞电话号码 from dual;
高乾竞电话号码----------------010-88888888转23
4.INITCAP回到数组并将数组的第二个拉丁字母转变成小写;SQL> select initcap(smith) upp from dual;
UPP-----Smith
5.INSTR(C1,C2,I,J)在两个数组中搜寻选定的字符串,回到辨认出选定的字符串的边线;C1 被搜寻的数组C2 期望搜寻的数组I 搜寻的已经开始边线,预设为1J 再次出现的边线,预设为1SQL> select instr(oracle traning,ra,1,2) instring from dual;
INSTRING---------9
6.LENGTH回到数组的长度;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回到数组,并将所有的字符串小写SQL> select lower(AaBbCcDd)AaBbCcDd from dual;
AABBCCDD--------aabbccdd
8.UPPER回到数组,并将所有的字符串小写SQL> select upper(AaBbCcDd) upper from dual;
UPPER--------AABBCCDD
9.RPAD和LPAD(粘贴字符串)RPAD 在列的右边粘贴字符串LPAD 在列的左边粘贴字符串SQL> select lpad(rpad(gao,10,*),17,*)from dual;
LPAD(RPAD(GAO,1-----------------*******gao*******不够字符串则用*来填满
10.LTRIM和RTRIMLTRIM 删除左边再次出现的数组RTRIM 删除右边再次出现的数组SQL> select ltrim(rtrim( gao qian jing , ), ) from dual;
LTRIM(RTRIM(-------------gao qian jing
11.SUBSTR(string,start,count)取子数组,从start已经开始,取count个SQL> select substr(13088888888,3,8) from dual;
SUBSTR(--------08888888
12.REPLACE(string,s1,s2)string 期望被替换的字符串或变量s1 被替换的数组s2 要替换的数组SQL> select replace(he love you,he,i) from dual;
REPLACE(HELOVEYOU,HE,I)------------------------------i love you
13.SOUNDEX回到两个与给定的数组读音相同的数组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 剪掉前面的字符串TRAILING 剪掉后面的字符串如果不选定,预设为空格符
15.ABS回到选定值的绝对值SQL> select abs(100),abs(-100) from dual;
ABS(100) ABS(-100)--------- ---------100 100
16.ACOS得出反余弦的值SQL> select acos(-1) from dual;
ACOS(-1)---------3.1415927
17.ASIN得出反正弦的值SQL> select asin(0.5) from dual;
ASIN(0.5)---------.52359878
18.ATAN回到两个数字的反正切值SQL> select atan(1) from dual;
ATAN(1)---------.78539816
19.CEIL回到大于或等于得出数字的最小有理数SQL> select ceil(3.1415927) from dual;
CEIL(3.1415927)---------------4
20.COS回到两个给定数字的余弦SQL> select cos(-3.1415927) from dual;
COS(-3.1415927)----------------1
21.COSH回到两个数字反余弦值SQL> select cosh(20) from dual;
COSH(20)---------242582598
22.EXP回到两个数字e的n次方根SQL> select exp(2),exp(1) from dual;
EXP(2) EXP(1)
--------- ---------7.3890561 2.7182818
23.FLOOR对给定的数字取有理数SQL> select floor(2345.67) from dual;
FLOOR(2345.67)--------------2345
24.LN回到两个数字的对数值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)回到两个以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)回到两个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回到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按照选定的精度进行舍入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回到1,小于0回到-1,等于0回到0SQL> select sign(123),sign(-100),sign(0) from dual;
SIGN(123) SIGN(-100) SIGN(0)--------- ---------- ---------1 -1 0
30.SIN回到两个数字的正弦值SQL> select sin(1.57079) from dual;
SIN(1.57079)------------1
31.SIGH回到双曲正弦的值SQL> select sin(20),sinh(20) from dual;
SIN(20) SINH(20)--------- ---------.91294525 242582598
32.SQRT回到数字n的根SQL> select sqrt(64),sqrt(10) from dual;
SQRT(64) SQRT(10)--------- ---------8 3.1622777
33.TAN回到数字的正切值SQL> select tan(20),tan(10) from dual;
TAN(20) TAN(10)--------- ---------2.2371609 .64836083
34.TANH回到数字n的双曲正切值SQL> select tanh(20),tan(20) from dual;
TANH(20) TAN(20)--------- ---------1 2.2371609
35.TRUNC按照选定的精度截取两个数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回到日期的最后一天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)得出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)得出在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)得出日期date和星期x之后计算下两个星期的日期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)按照得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将字符串数据类型转换为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)将源数组 sset从两个语言字符串集转换到另两个目的dset字符串集SQL> select convert(strutz,we8hp,f7dec) "conversion" from dual;
conver------strutz
44.HEXTORAW将两个十六进制构成的数组转换为二进制
45.RAWTOHEXT将两个二进制构成的数组转换为十六进制
46.ROWIDTOCHAR将ROWID数据类型转换为字符串类型
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)将数组转化为ORACLE中的两个日期
49.TO_MULTI_BYTE将数组中的单字节字符串转化为多字节字符串SQL> select to_multi_byte(高) from dual;
TO--高
50.TO_NUMBER将得出的字符串转换为数字SQL> select to_number(1999) year from dual;
YEAR---------1999
51.BFILENAME(dir,file)选定两个外部二进制文件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表达式以fmt选定的内部数字格式回到两个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()这三个表达式都是用来对大数据类型字段进行初始化操作的表达式
55.GREATEST回到一组表达式中的最大值,即比较字符串的编码大小.SQL> select greatest(AA,AB,AC) from dual;
GR--ACSQL> select greatest(啊,安,天) from dual;
GR--天
56.LEAST回到一组表达式中的最小值SQL> select least(啊,安,天) from dual;
LE--啊
57.UID回到标识当前用户的唯一有理数SQL> show userUSER 为"GAO"SQL> select username,user_id from dba_users where user_id=uid;
USERNAME USER_ID------------------------------ ---------GAO 25
58.USER回到当前用户的名字SQL> select user from dual;
USER------------------------------GAO
59.USEREVN回到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如果是则回到trueSQL> select userenv(isdba) from dual;
USEREN------FALSESQL> select userenv(isdba) from dual;
USEREN------TRUESESSION回到会话标志SQL> select userenv(sessionid) from dual;
USERENV(SESSIONID)--------------------152ENTRYID回到会话人口标志SQL> select userenv(entryid) from dual;
USERENV(ENTRYID)------------------0INSTANCE回到当前INSTANCE的标志SQL> select userenv(instance) from dual;
USERENV(INSTANCE)-------------------1LANGUAGE回到当前环境变量SQL> select userenv(language) from dual;
USERENV(LANGUAGE)----------------------------------------------------SIMPLIFIED CHINESE_CHINA.ZHS16GBKLANG回到当前环境的语言的缩写SQL> select userenv(lang) from dual;
USERENV(LANG)----------------------------------------------------ZHSTERMINAL回到用户的终端或机器的标志SQL> select userenv(terminal) from dual;
USERENV(TERMINA----------------GAOVSIZE(X)回到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
