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������ˤϡ�SPI����Ѥ������˴�ñ���㤬����ޤ��� execq �ץ����������1���ܤΰ����Ȥ���SQL���ޥ�ɤ�2���ܤΰ����Ȥ��ƹԿ���Ȥꡢ SPI_exec ���ޥ�ɤ�¹Ԥ������Υ��ޥ�ɤǽ������줿�Կ����֤��ޤ��� SPI�Τ��ʣ������ϥ������ĥ꡼��� src/test/regress/regress.c �� contrib/spi �ˤ���ޤ���

#include "executor/spi.h"

int execq(text *sql, int cnt);

int
execq(text *sql, int cnt)
{
    char *command;
    int ret;
    int proc;

    /* Ϳ����줿�ƥ����ȥ��֥������Ȥ�Cʸ������Ѵ� */
    command = DatumGetCString(DirectFunctionCall1(textout,
                                                  PointerGetDatum(sql)));

    SPI_connect();
    
    ret = SPI_exec(command, cnt);
    
    proc = SPI_processed;
    /*
     * ���줬SELECT�ʤɿ��Ԥ���Ф���ΤǤ���С�
     * �Ԥ�elog(INFO)����Ѥ���ɽ��
     */
    if (ret == SPI_OK_SELECT && SPI_processed > 0)
    {
        TupleDesc tupdesc = SPI_tuptable->tupdesc;
        SPITupleTable *tuptable = SPI_tuptable;
        char buf[8192];
        int i, j;
        
        for (j = 0; j < proc; j++)
        {
            HeapTuple tuple = tuptable->vals[j];
            
            for (i = 1, buf[0] = 0; i <= tupdesc->natts; i++)
                snprintf(buf + strlen (buf), sizeof(buf) - strlen(buf), " %s%s",
                        SPI_getvalue(tuple, tupdesc, i),
                        (i == tupdesc->natts) ? " " : " |");
            elog (INFO, "EXECQ: %s", buf);
        }
    }

    SPI_finish();
    pfree(command);

    return (proc);
}

(�����ʬ����䤹�����뤿��ˤ��δؿ��ϸƤӽФ�����Version-0����Ѥ��Ƥ��ޤ��� �ºݤΥ��ץꥱ�������Ǥϡ�������Version-1���󥿥ե���������Ѥ��٤��Ǥ���)

�ʲ��ϡ�����ѥ��뤷��ͭ�饤�֥������������ǡ��ؿ������������ˡ�Ǥ���

CREATE FUNCTION execq(text, integer) RETURNS integer
    AS 'filename'
    LANGUAGE C;

�ʲ��ϥ��å�������Ǥ���

=> SELECT execq('CREATE TABLE a (x integer)', 0);
 execq
-------
     0
(1 row)

=> INSERT INTO a VALUES (execq('INSERT INTO a VALUES (0)', 0));
INSERT 167631 1
=> SELECT execq('SELECT * FROM a', 0);
INFO:  EXECQ:  0    -- execq�ˤ�ä��������줿
INFO:  EXECQ:  1    -- execq�ˤ�ä��֤��졢��̤�INSERT�ˤ�ä��������줿

 execq
-------
     2
(1 row)

=> SELECT execq('INSERT INTO a SELECT x + 2 FROM a', 1);
 execq
-------
     1
(1 row)

=> SELECT execq('SELECT * FROM a', 10);
INFO:  EXECQ:  0
INFO:  EXECQ:  1
INFO:  EXECQ:  2    -- ���ꤵ�줿��0 + 2�Ȥ���1�ĤιԤΤߤ��������줿

 execq
-------
     3              -- 10�Ϻ����ͤ򼨤��Τߤǡ�3���ºݤιԿ��Ǥ���
(1 row)

=> DELETE FROM a;
DELETE 3
=> INSERT INTO a VALUES (execq('SELECT * FROM a', 0) + 1);
INSERT 167712 1
=> SELECT * FROM a;
 x
---
 1                  -- a�ơ��֥�˹Ԥ��ʤ�(0) + 1
(1 row)

=> INSERT INTO a VALUES (execq('SELECT * FROM a', 0) + 1);
INFO:  EXECQ:  0
INSERT 167713 1
=> SELECT * FROM a;
 x
---
 1
 2                  -- a�ơ��֥��1�Ԥ��� + 1
(2 rows)

--   ����ϥǡ����ѹ��˴ؤ���Ļ�����§���������ޤ���

=> INSERT INTO a SELECT execq('SELECT * FROM a', 0) * x FROM a;
INFO:  EXECQ:  1
INFO:  EXECQ:  2
INFO:  EXECQ:  1
INFO:  EXECQ:  2
INFO:  EXECQ:  2
INSERT 0 2
=> SELECT * FROM a;
 x
---
 1
 2
 2                  -- 2 �� * 1 (x�Ϻǽ�ι�)
 6                  -- 3 �� (2 + �������줿 1) * 2 (2���ܤ�x)
(4 rows)               ^^^^^^ 
                       �̤θƤӽФ��� execq()�DzĻ�ʹ�