Postgres的10進制與16進制互相轉換 1.10進制轉16進制 Postgres里面有一個內置的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 --------

Postgres的10進制與16進制互相轉換

1.10進制轉16進制

Postgres里面有一個內置的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';

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