Oracle 字符函数

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chr()

select chr(65 + level -1) from dual connect by level <= 10;

返回10行，分别是A-J

ascii()

select ascii('A') + level -1 from dual connect by level <= 10;

返回A-J的ascii值

to_number进制转换

10-->16

select to_number(10,'xxxx') from dual;

select to_number(10,'fmxxxx') from dual;

16-->10

select to_number('A','xx') from dual;

INSTR(string, substring, start_position, occurrence);

返回substring在string中的下标。1为起点。start_position 为正，从左至右查找，为负，从右到左查找。

SELECT INSTR('CORPORATE FLOOR','OR', 3, 2) "Instring"FROM DUAL;Instring----------14SELECT INSTR('CORPORATE FLOOR','OR', -3, 2) "Reversed Instring"FROM DUAL;Reversed Instring-----------------2

假如指定的occurrence不存在，则返回0

$hr@ORCL> select instr('abc','a',1,10) from dual;INSTR('ABC','A',1,10)---------------------                    0

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