ORACLE 获取varchar2字段范围内的较大值和较小值

Question

我有一个 table 字段类型为 varchar2，

假设这个值：

我需要获取以2开头的更大的值。

我正在尝试：

Select TO_NUMBER(myfield) from Services where myfield like '2%';

我明白了

现在，我想获得更大和更小的值25和2500000。

我正在尝试：

Select TO_NUMBER(myfield) from Services where myfield like '2%' ORDER BY myfield DESC;

和

Select MAX(TO_NUMBER(myfield)) from Services where myfield like '2%';

Select MIN(TO_NUMBER(myfield)) from Services where myfield like '2%';

我得到：

01722. 00000 -  "invalid number"
*Cause:    The specified number was invalid.
*Action:   Specify a valid number.

Answer 1

无论该行是否是结果集的一部分，Oracle 都会执行大多数函数调用。为确保仅针对结果集的值调用该函数，请将 where 条件放在子查询中：

Select TO_NUMBER(myfield) 
  from (SELECT * from Services where myfield like '2%')
 ORDER BY 1 DESC

如果您不确定，table 的每个值都是一个数字，最好编写您自己的 pl/sql 函数：

CREATE FUNCTION my_to_number(val IN VARCHAR2) RETURN NUMBER IS
BEGIN 
  RETURN TO_NUMBER(val);
EXCEPTION
  WHEN VALUE_ERROR THEN 
    RETURN NULL;
END;

然后使用此函数获取您的值：

Select MY_TO_NUMBER(myfield) 
  from Services where myfield like '2%'
 ORDER BY 1 DESC

Answer 2

您需要验证所有数字都是 number/digits。

包括此验证

 SELECT * FROM Services WHERE myfield LIKE '2%' AND REGEXP_LIKE (myfield, '^[[:digit:]]+$')

获取最大值和最小值

SELECT MAX(TO_NUMBER(myfield)), MIN(TO_NUMBER(myfield))
from (SELECT * FROM Services WHERE myfield LIKE '2%' AND REGEXP_LIKE (myfield, '^[[:digit:]]+$'))

现在，继Radagast81之后，

SELECT TO_NUMBER(myfield)
    from (SELECT * FROM Services WHERE myfield LIKE '3%' AND REGEXP_LIKE (myfield, '^[[:digit:]]+$'))
ORDER BY 1 DESC;

ORACLE 获取varchar2字段范围内的较大值和较小值

ORACLE Obtain the greater and lower value in a varchar2 field range

oracle

numbers

max

min

varchar2