如何在DB2上将十六进制转换为十进制

Question

I have a field in a db2 database which is on hexadecimal format ie 0x0a which is number 10 in decimal format. The hex field's datatype is char(1) for bit data .

hex(myfield) gives me the hexadecimal 0A

How can i convert 0x0a to 10 in a query on db2?

I have tried: cast(hex(myfield),integer) and int(hex(myfield)) with no luck.

Is it possible?

Answer 1

AFAIK, there is no such single function built into DB2 that would perform that conversion, but there is a blog post showing how to define such a function . The following function is taken from that article:

--#SET TERMINATOR @
CREATE OR REPLACE FUNCTION HEX2INT(str VARCHAR(8))
RETURNS INTEGER
SPECIFIC HEX2INT
DETERMINISTIC NO EXTERNAL ACTION CONTAINS SQL
BEGIN ATOMIC
  DECLARE res INTEGER  DEFAULT 0;
  DECLARE pos INTEGER DEFAULT 1;
  DECLARE nibble CHAR(1);
  WHILE pos <= LENGTH(str) DO
    SET nibble = SUBSTR(str, pos, 1);
    SET res = BITOR(CASE WHEN BITAND(res, 134217728) != 0
                         THEN BITOR(16 * BITANDNOT(res, 134217728),
                                    -2147483648)
                         ELSE 16 * res END,
                    CASE nibble
                         WHEN '0' THEN 0
                         WHEN '1' THEN 1
                         WHEN '2' THEN 2
                         WHEN '3' THEN 3
                         WHEN '4' THEN 4
                         WHEN '5' THEN 5
                         WHEN '6' THEN 6
                         WHEN '7' THEN 7
                         WHEN '8' THEN 8
                         WHEN '9' THEN 9
                         WHEN 'A' THEN 10
                         WHEN 'a' THEN 10
                         WHEN 'B' THEN 11
                         WHEN 'b' THEN 11
                         WHEN 'C' THEN 12
                         WHEN 'c' THEN 12
                         WHEN 'D' THEN 13
                         WHEN 'd' THEN 13
                         WHEN 'E' THEN 14
                         WHEN 'e' THEN 14
                         WHEN 'F' THEN 15
                         WHEN 'f' THEN 15
                         ELSE RAISE_ERROR('78000', 'Not a hex string') 
                         END),
        pos = pos + 1;
  END WHILE;
  RETURN res;
END
@
--#SET TERMINATOR ;

There are more functions for various conversion operations described.

Answer 2

I'm sure you could simplify the following

WITH fred (x) AS (VALUES 'f1'),

 nurk (a) as (SELECT UPPER(substr(x,1)) from fred 
              union all 
              select UPPER(substr(a,2)) from nurk 
               where substr(a,1,1) <> ' '), 

 bare (b, c) as (select substr(a,1,1), (length(a) - 1) 
              from nurk), 

 trap (d) as ((SELECT (ASCII(B) - ASCII('7')) * 
               power(16,c) 
               FROM BARE 
               WHERE (B BETWEEN 'A' AND 'F') 
               and 
               c <> -1) 
               union 
              (SELECT (ASCII(B) - ASCII('0')) * 
               power(16,c) 
               FROM BARE 
               WHERE (B not BETWEEN 'A' AND 'F') 
               and 
               c <> -1)) 

select sum(d) from trap

ran as

db2 -f "filename of above"

gave result of

241

try testing with values other than f1

John Hennesy

Answer 3

In Standard SQL (I hope so):

with inp (val) as                                                
(values ('FF'), ('AB'), ('ABCDEF')),                             
     calc(val, urval, res, f) as                                 
(select case when length(val) > 1                                
                  then substr(val, 1, length(val)-1)             
             else '' end, val,                                   
        locate(right(val, 1),'0123456789ABCDEF')-1, 16           
 from   inp                                                      
 union  all                                                      
 select case when length(val) > 1                                
                  then substr(val, 1, length(val)-1)             
             else '' end, urval,                                 
        res + ((locate(right(val, 1),'0123456789ABCDEF')-1) * f),
        f * 16                                                   
 from   calc                                                     
 where  length(val) > 0)                                         
select  urval, res 
from    calc                                     
where   val = ''        

==>

URVAL RES
FF 255
AB 171
ABCDEF 11.259.375

Answer 4

convert( datatype, column_Name)

Ex: convert(decimal(18,2), column_Name) --here column_Name has Hexadecimal value

Answer 5

The syntax is as follows

select CONVERT(int, 0xFFFFFF)

Check the documentation below should you need more details on converting to and from specific datatypes

Data types

https://technet.microsoft.com/en-us/library/ms187594(v=sql.105).aspx

Converting data types

https://technet.microsoft.com/en-us/library/ms191530(v=sql.105).aspx