vc6操作PostgreSQL 测试下异步通知接口

这个异步通知还很有用，就是一旦表里有数据写入了，马上通知你做其他什么事情

例子官方的是linux 的, 改成windows 吧，毕竟使用这个的人太少，霍霍

距离任务设定越来越短。接近完工鸟

准备工作：

 *   CREATE TABLE TBL1 (i int4);
 *
 *   CREATE TABLE TBL2 (i int4);
 *
 *   CREATE RULE r1 AS ON INSERT TO TBL1 DO
 *     (INSERT INTO TBL2 VALUES (new.i); NOTIFY TBL2);

   

  测试效果：

执行： INSERT INTO TBL1 VALUES (10);  执行 4次 程序退出

附上VC6  demo

// pgDemo.cpp : Defines the entry point for the console application.
//


#include "stdafx.h"
/*
 * testlibpq2.c
 *      Test of the asynchronous notification interface
 *
 * Start this program, then from psql in another window do
 *   NOTIFY TBL2;
 * Repeat four times to get this program to exit.
 *
 * Or, if you want to get fancy, try this:
 * populate a database with the following commands
 * (provided in src/test/examples/testlibpq2.sql):
 *
 *   CREATE TABLE TBL1 (i int4);
 *
 *   CREATE TABLE TBL2 (i int4);
 *
 *   CREATE RULE r1 AS ON INSERT TO TBL1 DO
 *     (INSERT INTO TBL2 VALUES (new.i); NOTIFY TBL2);
 *
 * and do this four times:
 *
 *   INSERT INTO TBL1 VALUES (10);
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <libpq-fe.h>


#include "winsock.h"
static void
exit_nicely(PGconn *conn)
{
    PQfinish(conn);
    exit(1);
}


int
main(int argc, char **argv)
{
    const char *conninfo;
    PGconn     *conn;
    PGresult   *res;
    PGnotify   *notify;
    int         nnotifies;


    /*
     * If the user supplies a parameter on the command line, use it as the
     * conninfo string; otherwise default to setting dbname=postgres and using
     * environment variables or defaults for all other connection parameters.
     */
    if (argc > 1)
        conninfo = argv[1];
    else
        //conninfo = "dbname = postgres";
conninfo = "dbname=mydb user=Eagle password=123456";




    /* Make a connection to the database */
    conn = PQconnectdb(conninfo);


    /* Check to see that the backend connection was successfully made */
    if (PQstatus(conn) != CONNECTION_OK)
    {
        fprintf(stderr, "Connection to database failed: %s",
                PQerrorMessage(conn));
        exit_nicely(conn);
    }


    /*
     * Issue LISTEN command to enable notifications from the rule's NOTIFY.
     */
    res = PQexec(conn, "LISTEN TBL2");
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
    {
        fprintf(stderr, "LISTEN command failed: %s", PQerrorMessage(conn));
        PQclear(res);
        exit_nicely(conn);
    }


    /*
     * should PQclear PGresult whenever it is no longer needed to avoid memory
     * leaks
     */
    PQclear(res);


    /* Quit after four notifies are received. */
    nnotifies = 0;
    while (nnotifies < 4)
    {
        /*
         * Sleep until something happens on the connection.  We use select(2)
         * to wait for input, but you could also use poll() or similar
         * facilities.
         */
        int         sock;
        fd_set      input_mask;


        sock = PQsocket(conn);


        if (sock < 0)
            break;              /* shouldn't happen */


        FD_ZERO(&input_mask);
        FD_SET(sock, &input_mask);


        if (select(sock + 1, &input_mask, NULL, NULL, NULL) < 0)
        {
            fprintf(stderr, "select() failed: %s\n", strerror(errno));
            exit_nicely(conn);
        }


        /* Now check for input */
        PQconsumeInput(conn);
        while ((notify = PQnotifies(conn)) != NULL)
        {
            fprintf(stderr,
                    "ASYNC NOTIFY of '%s' received from backend PID %d\n",
                    notify->relname, notify->be_pid);
            PQfreemem(notify);
            nnotifies++;
        }
    }


    fprintf(stderr, "Done.\n");


    /* close the connection to the database and cleanup */
    PQfinish(conn);


    return 0;
}

效果图 2张：