SQL中的單記錄函數
1.ASCII 返回與指定的字符對應的十進制數;
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 給出整數,返回對應的字符;
SQL> select chr(54740) zhao,chr(65) chr65 from dual;
ZH C
-- -
趙 A
3.CONCAT 連接兩個字符串;
SQL> select concat('010-','88888888')||'轉23'? 高乾競電話 from dual;
高乾競電話
----------------
010-88888888轉23
4.INITCAP 返回字符串并將字符串的第一個字母變為大寫;
SQL> select initcap('smith') upp from dual;
UPP
-----
Smith
5.INSTR(C1,C2,I,J) 在一個字符串中搜索指定的字符,返回發現指定的字符的位置;
C1??? 被搜索的字符串
C2??? 希望搜索的字符串
I???? 搜索的開始位置,默認為1
J???? 出現的位置,默認為1
SQL> select instr('oracle traning','ra',1,2) instring from dual;
INSTRING
---------
9
6.LENGTH 返回字符串的長度;
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))
------ ------------ ---------------- ------------ --------- --------------------
高乾競??????????? 3 北京市海錠區??????????????? 6?? 9999.99??????????????????? 7
7.LOWER 返回字符串,并將所有的字符小寫
SQL> select lower('AaBbCcDd')AaBbCcDd from dual;
AABBCCDD
--------
aabbccdd
8.UPPER 返回字符串,并將所有的字符大寫
SQL> select upper('AaBbCcDd') upper from dual;
UPPER
--------
AABBCCDD
9.RPAD和LPAD(粘貼字符)
RPAD? 在列的右邊粘貼字符
LPAD? 在列的左邊粘貼字符
SQL> select lpad(rpad('gao',10,'*'),17,'*')from dual;
LPAD(RPAD('GAO',1
-----------------
*******gao*******
不夠字符則用*來填滿
10.LTRIM和RTRIM
LTRIM? 刪除左邊出現的字符串
RTRIM? 刪除右邊出現的字符串
SQL> select ltrim(rtrim('?? gao qian jing?? ',' '),' ') from dual;
LTRIM(RTRIM('
-------------
gao qian jing
11.SUBSTR(string,start,count)
取子字符串,從start開始,取count個
SQL> select substr('13088888888',3,8) from dual;
SUBSTR('
--------
08888888
12.REPLACE('string','s1','s2')
string?? 希望被替換的字符或變量
s1?????? 被替換的字符串
s2?????? 要替換的字符串
SQL> select replace('he love you','he','i') from dual;
REPLACE('HELOVEYOU','HE','I')
------------------------------
i love you
13.SOUNDEX 返回一個與給定的字符串讀音相同的字符串
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,默認為空格符
15.ABS 返回指定值的絕對值
SQL> select abs(100),abs(-100) from dual;
ABS(100) ABS(-100)
--------- ---------
100?????? 100
16.ACOS 給出反余弦的值
SQL> select acos(-1) from dual;
ACOS(-1)
---------
3.1415927
17.ASIN 給出反正弦的值
SQL> select asin(0.5) from dual;
ASIN(0.5)
---------
.52359878
18.ATAN 返回一個數字的反正切值
SQL> select atan(1) from dual;
ATAN(1)
---------
.78539816
19.CEIL 返回大于或等于給出數字的最小整數
SQL> select ceil(3.1415927) from dual;
CEIL(3.1415927)
---------------
4
20.COS 返回一個給定數字的余弦
SQL> select cos(-3.1415927) from dual;
COS(-3.1415927)
---------------
-1
21.COSH 返回一個數字反余弦值
SQL> select cosh(20) from dual;
COSH(20)
---------
242582598
22.EXP 返回一個數字e的n次方根
SQL> select exp(2),exp(1) from dual;
EXP(2)??? EXP(1)
--------- ---------
7.3890561 2.7182818
23.FLOOR 對給定的數字取整數
SQL> select floor(2345.67) from dual;
FLOOR(2345.67)
--------------
2345
24.LN 返回一個數字的對數值
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) 返回一個以n1為底n2的對數
SQL> select log(2,1),log(2,4) from dual;
LOG(2,1)? LOG(2,4)
--------- ---------
0???????? 2