Query to find out if the numeric string has letters in it. Please, help!

Question

Hi, everyone!
Could you please help me in constructing the following query:
I want the query to return the records, for which a specified column contains at least 1 alpha-numeric character in it. For example, if I search the Items table, I want the rows with the following Item_Number values be returned: "34265af6", "bbbbbbbb", "9808677y" etc...
Thanks a lot.
Regards,
Eugene.

Answer 1

Would you consider the Null value for "p_string" input parameter as being NUMBER or otherwise? That's an interesting question. The function and query as is would treat nulls as numbers, consistent with how Oracle would treat a null as a potential number, by not raising any error when asked for to_number(null). However, if you wanted to exclude nulls, you could just add an additional filter condition to the where clause. See examples below.
-- selecting to_number(null) does not raise an error:
SQL> SELECT TO_NUMBER (NULL) FROM DUAL
  2  /
TO_NUMBER(NULL)                                                                
-- is_number(null) is considered numeric:
SQL> SELECT is_number (NULL) FROM DUAL
  2  /
IS_NUMBER(NULL)                                                                
Y                                                                              
-- combination of Oracle and user-defined
-- functions considers null as numeric:
SQL> SELECT DECODE (LTRIM (NULL, '0123456789-+E/.,'),
  2                NULL, is_number (NULL),
  3                'N')
  4  FROM   DUAL
  5  /
DECODE(LTRIM(NULL,'0123456789-+E/.,'),NULL,IS_NUMBER(NULL),'N')                
Y                                                                              
SQL> -- additional test data:
SQL> INSERT INTO items VALUES (NULL)
  2  /
1 row created.
SQL> COMMIT
  2  /
Commit complete.
SQL> SELECT * FROM items
  2  /
ITEM_NUMBE                                                                     
ABC123                                                                         
ABC                                                                            
DEF123                                                                         
123                                                                            
C123                                                                           
XYZ                                                                            
GHI                                                                            
8 rows selected.
SQL>
SQL>
SQL> -- unmodified select statement
SQL> -- treats nulls as numbers
SQL> -- and doesn't include null value
SQL> -- in result set when searching
SQL> -- for non-numbers:
SQL> SELECT *
  2  FROM   items
  3  WHERE  DECODE (LTRIM (item_number, '0123456789-+E/.,'),
  4                NULL, is_number (item_number),
  5                'N') = 'N'
  6  /
ITEM_NUMBE                                                                     
ABC123                                                                         
ABC                                                                            
DEF123                                                                         
C123                                                                           
XYZ                                                                            
GHI                                                                            
6 rows selected.
SQL>
SQL>
SQL> -- modified select statement
SQL> -- treats nulls as non-numbers
SQL> -- and includes nulls in result set
SQL> -- when searching for non-numbers:
SQL> SELECT *
  2  FROM   items
  3  WHERE  DECODE (LTRIM (item_number, '0123456789-+E/.,'),
  4                NULL, is_number (item_number),
  5                'N') = 'N'
  6  OR     item_number IS NULL
  7  /
ITEM_NUMBE                                                                     
ABC123                                                                         
ABC                                                                            
DEF123                                                                         
C123                                                                           
XYZ                                                                            
GHI                                                                            
7 rows selected.