批处理函数

libpq提供PQexecParamsBatch接口实现批处理功能，比PQexecParams接口多了nBatch参数，参数说明如下：

示例

#include <stdio.h>
#include <stdlib.h>
#include "libpq-fe.h"

static void
exit_nicely(PGconn *conn)
{
	PQfinish(conn);
	exit(1);
}

int main(int argc, char **argv)
{
	const char *conninfo;
	PGconn	   *conn;
	PGresult   *res;
    int i;
    conninfo = "host = localhost user = libpq password = Aa@123 dbname = vastbase port =25638";

	/* 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, "%s", PQerrorMessage(conn));
		exit_nicely(conn);
	}

    res = PQexec(conn, "drop table if exists test;create table test(id integer,name varchar(50));");
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "sql failed: %s", PQerrorMessage(conn));
		PQclear(res);
		exit_nicely(conn);
	}
    else
    {
        printf("sql success\n");
    }
    PQclear(res);

    const char command[] = "INSERT INTO test (id, name)"
                         "VALUES($1::integer, $2::varchar(50))";
    int nParams = 2;
    int nBatchCount=4;
    const Oid paramTypes[] = {23,1043};
    int binaryVal1 = htonl(1);
    int binaryVal2 = htonl(2);
    int binaryVal3 = htonl(3);
    int binaryVal4 = htonl(4);
    const char *const paramValues[][2]={{(const char *)&binaryVal1,"123"},
                                    {(const char *)&binaryVal2,"234"},
                                    {(const char *)&binaryVal3,"345"},
                                    {(const char *)&binaryVal4,"456"}};
    const int paramLengths[][2] = {{sizeof(int), 3},{sizeof(int), 3},{sizeof(int), 3},{sizeof(int), 3}};
    const int paramFormats[] = {1, 1};
    int resultFormat = 0;

    printf("-----test batch insert -----\n");
    res = PQexecParamsBatch(conn,     /*连接句柄*/
                    command,     /* SQL文本串 */
                    nParams ,		 /* 参数个数*/
                    nBatchCount,  /* 批量操作数*/
                    paramTypes,	 /*绑定参数类型*/
                    paramValues[0],  /*绑定参数的值*/
                    paramLengths[0],	/* 参数长度*/
                    paramFormats, 	/* 参数格式（文本或二进制） */
                    resultFormat);		/* 返回结果格式（文本或二进制) */
    if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "batch insert failed: %s", PQerrorMessage(conn));
		PQclear(res);
		exit_nicely(conn);
	}
    else
    {
        printf("batch insert success\n");
    }

    PQclear(res);
    printf("-----print result -----\n");
    res = PQexec(conn, "select * from test;");
    for (i = 0; i < PQntuples(res); i++)
    {
        const char* id = NULL;
        const char* name = NULL;
        id = PQgetvalue(res, i, 0);
        name = PQgetvalue(res, i, 1);
        printf("id = %s, name = %s \n", id, name);
    }

    PQclear(res);
    PQfinish(conn);
    return 0;
}