PostgreSQL 8.4.4ʸ��
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41.1. PL/Python�ؿ�

PL/Python�Ǻ��줿�ؿ��ɸ��CREATE FUNCTION��ʸ��ޤ��

CREATE FUNCTION funcname (argument-list)
  RETURNS return-type
AS $$
  # PL/Python function body
$$ LANGUAGE plpythonu;

�ؿ��Τ�ñ�ʤ�Python��ץȤǤ�� ؿ��ƤӽФ��ȡ��args[]��ǤȤ��ơ��ޤ��̾��դ��ΰ��̾��ѿ��Ȥ��Python��ץȤ��Ϥ��ޤ�� ̤ϡ�Python��ɤ��̾��ˡ��return�ޤ��yield�ʷ�̥��å�ʸ�ξ��ˤ��֤��ΤǤ��

��Ȥ��С�2�Ĥ��礭�ʿ��֤��ؿ��ϰʲ��Τ褦��뤳�Ȥ��Ǥ��ޤ��

CREATE FUNCTION pymax (a integer, b integer)
  RETURNS integer
AS $$
  if a > b:
    return a
  return b
$$ LANGUAGE plpythonu;

�ؿ��ΤȤ��󶡤��줿Python�Υ��ɤ�Python�δؿ��Ѵ��ޤ�� 㤨�о��ϰʲ��Τ褦�ˤʤ�ޤ��

def __plpython_procedure_pymax_23456():
  if a > b:
    return a
  return b

��ǡ�23456��PostgreSQL�ˤ��Ƥ�줿��δؿ��OID�Ǥ��

PostgreSQL�ؿ��ѥ�᡼��args��Х�ꥹ�Ȥ��Ѳ�ǽ�Ǥ�� pymax��ˤ��ȡ�args[0]�ˤϺǽ�ΰ��Ȥ��Ϥ��줿��Τ��ޤޤ졢args[1]�ˤ�2��ܤΰ��ͤ��ޤޤ�ޤ�� ̤��ˡ�Ȥ��ơ��Τ褦��̾��դ��ѥ�᡼��Ѥ��뤳�Ȥ��Ǥ��ޤ�� ̾��դ��ѥ�᡼��Ѥ��뤳�Ȥ��̾��ޤ��

SQL��NULL�ͤ��ؿ��Ϥ��ȡ��ΰ��ͤ�Python.�Ǥ�None�Ȥʤ�ޤ�� δؿ��Ǥϡ�NULL��ϤǤϴְ�ä��̤��֤��ޤ�� ؿ��STRICT��Ϳ��PostgreSQL��NULL�ͤ��Ϥ��줿��ˤ��δؿ��ƤӽФ��ưŪ��ñ��NULL��̤��֤��Ȥ��Ū��ư���뤳�Ȥ��Ǥ��ޤ�� ¾�ˡ��ؿ��Τ�NULL��Ϥ򸡺��뤳�Ȥ�Ǥ��ޤ��

CREATE FUNCTION pymax (a integer, b integer)
  RETURNS integer
AS $$
  if (a is None) or (b is None):
    return None
  if a > b:
    return a
  return b
$$ LANGUAGE plpythonu;

��Ǽ��褦�ˡ�PL/Python�ؿ��SQL NULL�ͤ��֤��ˤϡ�None�Ȥ��ͤ��֤��Ƥ�� ؿ��̩�Ȥ��Ǥ⸷̩�Ȥ��ʤ��Ǥ⡢��Ԥ��Ȥ��Ǥ��ޤ��

ʣ�緿�ΰ��Python�ΥޥåפȤ��Ϥ��ޤ�� ޥåפ��̾��ʣ�緿��°��̾�Ǥ�� Ϥ��줿�Ԥ�°��ͤ�NULL�ξ�硢�ޥå׾�Ǥ�None�Ȥ��ͤȤʤ�ޤ�� ʲ��򼨤��ޤ��

CREATE TABLE employee (
  name text,
  salary integer,
  age integer
);

CREATE FUNCTION overpaid (e employee)
  RETURNS boolean
AS $$
  if e["salary"] > 200000:
    return True
  if (e["age"] < 30) and (e["salary"] > 100000):
    return True
  return False
$$ LANGUAGE plpythonu;

Python�ؿ��Ԥޤ��ʣ�緿��֤��ˡ��ʣ��¸�ߤ��ޤ�� ʲ��Ǥ�

CREATE TYPE named_value AS (
  name   text,
  value  integer
);

��Ȥ��ޤ�� ʣ�緿�η�̤ϰʲ��Τ褦��֤��ޤ��

��ʥ��ץ�ޤ��ϥꥹ�ȡˤ��set ��Բġʥ��ǥå��դ��Ǥ��ʤ��

�֤��֥��Ȥϡ��̤�ʣ�緿��ĥե��ɤ�Ʊ��ܿ��⤿�ʤ��Фʤ�ޤ�� 0�Ȥ��ǥå��ι��ܤ�ʣ�緿�κǽ�Υե��ɡ�1��Υե��ɡ��Ȥʤ�ޤ�� ʲ��򼨤��ޤ��

CREATE FUNCTION make_pair (name text, value integer)
  RETURNS named_value
AS $$
  return [ name, value ]
  # or alternatively, as tuple: return ( name, value )
$$ LANGUAGE plpythonu;

Ǥ�դ��SQL NULL�ͤ��֤��ˤϡ��б��֤�None��ޤ��

�ޥåסʼ��

��̷��ͤϡ��̾�򥭡��Ȥ��ƻ��ĥޥåפ��Ф��ޤ�� ʲ��򼨤��ޤ��

CREATE FUNCTION make_pair (name text, value integer)
  RETURNS named_value
AS $$
  return { "name": name, "value": value }
$$ LANGUAGE plpythonu;

;�פʼ��Υ��ͤ��Ȥ߹�碌��̵�뤵��ޤ�� ¸�ߤ��ʤ��ϥ��顼�Ȥ��ư��ޤ�� Ǥ�դ��SQL NULL��֤��ˤϡ��б��̾�򥭡��Ȥ��None��Ƥ��

��֥��ȡ�__getattr__�᥽�åɤ��󶡤��Ǥ�դΥ��֥��ȡ�

��ϥޥåפ�Ʊ��褦��ư��ޤ�� ʲ��򼨤��ޤ��

CREATE FUNCTION make_pair (name text, value integer)
  RETURNS named_value
AS $$
  class named_value:
    def __init__ (self, n, v):
      self.name = n
      self.value = v
  return named_value(name, value)

  # or simply
  class nv: pass
  nv.name = name
  nv.value = value
  return nv
$$ LANGUAGE plpythonu;

��ͤ��Ѱդ��Ƥ��ʤ��硢Python�ϥǥե��Ȥ�None��֤��ޤ�� PL/Python�ϡ�Python��None��SQL��NULL�ͤ��Ѵ��ޤ��

�ޤ��PL/Python�ؿ��ϥ��ޤ��ʣ�緿�ν��֤��Ȥ�Ǥ��ޤ�� ֤��륪�֥��Ȥ��Ū�˥��ƥ졼��Ѵ��뤿�ᡢʣ��μ¸��ˡ��ޤ�� ʲ��Ǥϡ��ʲ��ʣ�緿��¸�ߤ��뤳�Ȥ��ꤷ�ޤ��

CREATE TYPE greeting AS (
  how text,
  who text
);

��Ȥ��̤ϰʲ��֤��ޤ��

��ʥ��ץ롢�ꥹ�ȡ��åȡ�

CREATE FUNCTION greet (how text)
  RETURNS SETOF greeting
AS $$
  # return tuple containing lists as composite types
  # all other combinations work also
  return ( [ how, "World" ], [ how, "PostgreSQL" ], [ how, "PL/Python" ] )
$$ LANGUAGE plpythonu;

��ƥ졼��__iter__�᥽�åɤ�next�᥽�åɤ��󶡤��Ǥ�դΥ��֥��ȡ�

CREATE FUNCTION greet (how text)
  RETURNS SETOF greeting
AS $$
  class producer:
    def __init__ (self, how, who):
      self.how = how
      self.who = who
      self.ndx = -1

    def __iter__ (self):
      return self

    def next (self):
      self.ndx += 1
      if self.ndx == len(self.who):
        raise StopIteration
      return ( self.how, self.who[self.ndx] )

  return producer(how, [ "World", "PostgreSQL", "PL/Python" ])
$$ LANGUAGE plpythonu;

��ͥ졼��(yield)

CREATE FUNCTION greet (how text)
  RETURNS SETOF greeting
AS $$
  for who in [ "World", "PostgreSQL", "PL/Python" ]:
    yield ( how, who )
$$ LANGUAGE plpythonu;

警告

��Ǥϡ�Python bug #1483133�Τ��ᡢ��Python 2.4�ǥХå��ǡ�--with-pydebug��ץ��դ��/��ѥ��뤵�줿Python�ˤ��̤��֤��˥��ƥ졼��Ѥ��PostgreSQL��Ф򥯥�å��夵��뤳�Ȥ��狼�äƤ��ޤ�� ̤�ѥå��Fedora 4�ˤϤ��Զ�礬��ޤ�� Python��Ǥ�ѥå�Ŭ�ѺѤߤ�Fedora 4�ǤϤ��ϵ��ޤ��

��Х��SD��ϡ��ؿ��ƤӽФ��֤Υǡ��¸�Τ��˻��Ѥ��뤳�Ȥ��Ǥ��ޤ�� ѿ��ϥץ饤�١��Ȥ��Ū�ǡ��Ǥ�� Х��GD��ϡ��ͭ�ǡ��Ǥ��ꡢ��å��Ƥ�Python�ؿ��ǻ��Ѥ��뤳�Ȥ��Ǥ��ޤ�� դ��ƻ��Ѥ��Ƥ��

�ƴؿ��ϡ�Python��󥿥ץ꥿��Ǽ��Ȥμ¹ԴĶ��ꤷ�ޤ�� Τ��ᡢmyfunc�ˤ�륰��Х�ǡ��ȴؿ��ΰ��myfunc2��Ѥ��뤳�ȤϤǤ��ޤ�� 嵭��̤ꡢGD��Υǡ��㳰�Ǥ��

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