【DB笔试面试458】在Oracle中，如何判断一个字符串是否全为数字？

SYS@PROD1> SELECT 
  2     NVL2(TRANSLATE(REPLACE('12','.',''),'/1234567890','/'),'CHAR','NUMBER') IN_TYPE,
  3     NVL2(TRANSLATE(REPLACE('12.34','.',''),'/1234567890','/'),'CHAR','NUMBER') IN_TYPE2,
  4     NVL2(TRANSLATE(REPLACE('12.Mabcd','.',''),'/1234567890','/'),'CHAR','NUMBER') IN_TYPE3 
  5  FROM DUAL;
IN_TYP IN_TYP IN_T
------ ------ ----

CREATE OR REPLACE FUNCTION ISNUMERIC(STR IN VARCHAR2) RETURN NUMBER IS
  V_STR FLOAT;
BEGIN
  IF STR IS NULL THEN
    RETURN 0;
  ELSE
    BEGIN
      SELECT TO_NUMBER(STR) INTO V_STR FROM DUAL;
    EXCEPTION
      WHEN INVALID_NUMBER THEN
        RETURN 0;
    END;
    RETURN 1;
  END IF;
END ISNUMERIC;

CREATE OR REPLACE FUNCTION ISNUMERIC(STR IN VARCHAR2) RETURN NUMBER IS
BEGIN
  IF STR IS NULL THEN
    RETURN 0;
  ELSE
    IF REGEXP_LIKE(STR, '(^[+-]?\d{0,}\.?\d{0,}$)') THEN
      RETURN 1;
    ELSE
      RETURN 0;
    END IF;
  END IF;
END ISNUMERIC;

CREATE OR REPLACE FUNCTION ISNUMERIC(STR IN VARCHAR2) RETURN NUMBER IS
  V_STR VARCHAR2(1000);
BEGIN
  IF STR IS NULL THEN
    RETURN 0;
  ELSE
    V_STR := TRANSLATE(STR, '.0123456789', '.');
    IF V_STR = '.' OR V_STR = '+.' OR V_STR = '-.' OR V_STR IS NULL THEN
      RETURN 1;
    ELSE
      RETURN 0;
    END IF;
  END IF;
END ISNUMERIC;