PostgreSQL的10進制與16進制互轉

1.10進制轉16進制
Postgres裏面有一個內置的10進制轉16進制的函數:to_hex(int)/to_hex(bigint)

[postgres@localhost ~]$ psql
Password: 
psql (9.1.3)
Type "help" for help.

postgres=# select to_hex(9);
 to_hex 
--------
 9
(1 row)

postgres=# select to_hex(17);
 to_hex 
--------
 11
(1 row)

postgres=# select to_hex(31);
 to_hex 
--------
 1f
(1 row)

postgres=# select to_hex(255);
 to_hex 
--------
 ff
(1 row)

postgres=# select to_hex(256);
 to_hex 
--------
 100
(1 row)

2.16進制轉10進制
沒有內置的，參考網上的一個例子

postgres=# CREATE FUNCTION
hex_to_dec(in_hex TEXT)
RETURNS INT
IMMUTABLE STRICT LANGUAGE sql AS
$body$
  SELECT CAST(CAST(('x' || CAST($1 AS text)) AS bit(8)) AS INT);
$body$;
CREATE FUNCTION
postgres=# select hex_to_dec('1f');
 hex_to_dec 
------------
         31
(1 row)

postgres=# select hex_to_dec('ff');
 hex_to_dec 
------------
        255
(1 row)

postgres=# select hex_to_dec('fe');
 hex_to_dec 
------------
        254
(1 row)

postgres=# select hex_to_dec('09');
 hex_to_dec 
------------
          9
(1 row)

postgres=# select hex_to_dec('11');
 hex_to_dec 
------------
         17
(1 row)

內置的函數說明,支持輸入是int或者bigint類型
to_hex(int/bigint):

CREATE OR REPLACE FUNCTION to_hex(integer)   RETURNS text AS 'to_hex32'   LANGUAGE internal IMMUTABLE STRICT   COST 1; ALTER FUNCTION to_hex(integer)   OWNER TO postgres; COMMENT ON FUNCTION to_hex(integer) IS 'convert int4 number to hex'; CREATE OR REPLACE FUNCTION to_hex(bigint)   RETURNS text AS 'to_hex64'   LANGUAGE internal IMMUTABLE STRICT   COST 1; ALTER FUNCTION to_hex(bigint)   OWNER TO postgres; COMMENT ON FUNCTION to_hex(bigint) IS 'convert int8 number to hex';

參考:http://postgresql.1045698.n5.nabble.com/Hex-to-Dec-Conversion-td3218223.html