oracle 判断字符串是否是数字

方法一：通过 To_Number 函数异常来判断
CREATE OR REPLACE FUNCTION Is_Number (
   str_    VARCHAR2 ) RETURN VARCHAR2
IS
   num_    NUMBER;
BEGIN
num_ := to_number(str_);
RETURN 'Y';
EXCEPTION
   WHEN OTHERS THEN
      RETURN 'N';
END Is_Number;
/

SQL> select Is_Number('12345') from dual;

IS_NUMBER('12345')
--------------------------------------------------------------------------------
Y

SQL> select Is_Number('123.45') from dual;

IS_NUMBER('123.45')
--------------------------------------------------------------------------------
Y

SQL> select Is_Number('123a') from dual;

IS_NUMBER('123A')
--------------------------------------------------------------------------------
N

SQL>

方法二：通过 translate函数来实现
SELECT nvl2(translate('123','/1234567890','/'),'CHAR','NUMBER')
FROM dual ;

SQL> SELECT nvl2(translate('123','/1234567890','/'),'CHAR','NUMBER')
2 FROM dual;

NVL2(TRANSLATE('123','/1234567
------------------------------
NUMBER

SQL>
SQL> SELECT nvl2(translate('123A','/1234567890','/'),'CHAR','NUMBER')
2 FROM dual;

NVL2(TRANSLATE('123A','/123456
------------------------------
CHAR

SQL>

　　在实际使用过程中，可以根据情况选用这两种方法。第一种方法的好处是可以判断带小数的数字，而第二种方法只能判断整数。因为如果 translate 函数如果写成 translate('123A','/1234567890.','/') 这种形式是会有问题的。

SQL> select Is_Number('123.45.6') from dual;

IS_NUMBER('123.45.6')
--------------------------------------------------------------------------------
N

SQL>
SQL> SELECT nvl2(translate('1234.5.6','/1234567890.','/'),'CHAR','NUMBER')
2 FROM dual;

NVL2(TRANSLATE('1234.5.6','/12
------------------------------
NUMBER

-----------------------------------------------

SELECT TRANSLATE('2KRW229', '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ', '0123456789') --把字符翻译成数字

"Translate example"

FROM DUAL;

Translate example

-----------------

2229

参考：https://blog.csdn.net/lzflydream/article/details/42592959