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1
J 出现的位置,默认为1
SQL> 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RTRIM
LTRIM 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
--------
weather
wether
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
