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【C】用c进行简单的postgresql操作
作者:OP菠菜 / 发布于2015/4/8/ 627

	#include <stdio.h>
	#include <string.h>
	#include <assert.h>
	#include <libpq-fe.h>
	
	#include "error.h"
	#include "pgsql.h"
	
	typedef struct tagInfo
	{
	 char name[24];
	 char age[8];
	 char birthday[24];
	}INFO_S;
	
	int main(int argc, char **argv)
	{
	 int ret, i = 0;
	 INFO_S stInfo;
	 DB_HANDLER_S stHandler;
	 //const char *command = "INSERT INTO usertbl(name, age, birthday) VALUES('win', 23, '1992-07-23');";
	 const char *command = "SELECT * FROM usertbl;";
	
	 memset(&stInfo, 0, sizeof(stInfo));
	 memset(&stHandler, 0, sizeof(stHandler));
	
	 ret = DB_Connect(&stHandler);
	 if (ERROR_SUCCESS != ret)
	 {
	 return ret;
	 }
	
	 ret = DB_Exec(&stHandler, command);
	 if (ERROR_SUCCESS != ret)
	 {
	 DB_Close(&stHandler);
	 return ret;
	 }
	
	 printf("affect rows:%ld, tuples:%ld, fields:%ld\r\n", stHandler.affect_rows, stHandler.tuples, stHandler.fields);
	
	 snprintf(stInfo.name, sizeof(stInfo.name), "%s", DB_Fetch(&stHandler, 0, i++));
	 snprintf(stInfo.age, sizeof(stInfo.age), "%s", DB_Fetch(&stHandler, 0, i++));
	 snprintf(stInfo.birthday, sizeof(stInfo.birthday), "%s", DB_Fetch(&stHandler, 0, i++));
	 printf("%s, %s, %s\r\n", stInfo.name, stInfo.age, stInfo.birthday);
	
	 DB_Close(&stHandler);
	
	 return ERROR_SUCCESS;
	}
	2. [文件] pgsql.c ~ 2KB 下载(1)
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	#include <stdio.h>
	#include <string.h>
	#include <stdlib.h>
	#include <assert.h>
	#include <libpq-fe.h>
	
	#include "error.h"
	#include "pgsql.h"
	
	static void db_ClearResult(DB_HANDLER_S *handler)
	{
	 if (NULL != handler->result)
	 {
	 PQclear(handler->result);
	 handler->result = NULL;
	 }
	
	 return;
	}
	
	int DB_Connect(DB_HANDLER_S *handler)
	
	{
	 const char *conninfo = "host='127.0.0.1' dbname='exampledb' user='dbuser' password='123456'";
	
	 assert(NULL != handler);
	
	 handler->connection = PQconnectdb(conninfo);
	 if (NULL == handler->connection)
	 {
	 printf("connect db failed !\r\n");
	 return ERROR_CONNECTDB_FAILED;
	 }
	
	 return ERROR_SUCCESS;
	}
	
	int DB_Exec(DB_HANDLER_S *handler, const char *command)
	{
	 db_ClearResult(handler);
	 handler->result = PQexec(handler->connection, command);
	 if (NULL == handler->result)
	 {
	 printf("db exec sql failed ! ERROR : %s\r\n", PQerrorMessage(handler->connection));
	 handler->exec_status = PGRES_FATAL_ERROR;
	 }
	 else
	 {
	 handler->exec_status = PQresultStatus(handler->result);
	 }
	
	 switch (handler->exec_status)
	 {
	 case PGRES_COMMAND_OK://insert
	 {
	 handler->affect_rows = strtoul(PQcmdTuples(handler->result), NULL, 0);
	 break;
	 }
	 case PGRES_TUPLES_OK://select
	 {
	 handler->tuples = (unsigned long) PQntuples(handler->result);
	 handler->fields = (unsigned long) PQnfields(handler->result);
	 break;
	 }
	 default:
	 {
	 printf("db exec sql failed ! ERROR : %s\r\n", PQerrorMessage(handler->connection));
	 break;
	 }
	 }
	
	 return ERROR_SUCCESS;
	}
	
	char *DB_Fetch(DB_HANDLER_S *handler, unsigned long tuple, unsigned long field)
	{
	 return PQgetvalue(handler->result, tuple, field);
	}
	
	void DB_Close(DB_HANDLER_S *handler)
	{
	 db_ClearResult(handler);
	 PQfinish(handler->connection);
	 handler->connection = NULL;
	
	 return;
	}

	

	

	

	#ifndef PGSQL_H
	#define PGSQL_H
	
	typedef struct tagDBHandler
	{
	 PGconn *connection;
	 ExecStatusType exec_status;
	 PGresult *result;
	 unsigned long affect_rows; /*for insert, update, delete*/
	 unsigned long tuples; /*for select*/
	 unsigned long fields; /*for select*/
	}DB_HANDLER_S;
	
	int DB_Connect(DB_HANDLER_S *handler)
	;
	int DB_Exec(DB_HANDLER_S *handler, const char *command);
	char *DB_Fetch(DB_HANDLER_S *handler, unsigned long tuple, unsigned long field);
	void DB_Close(DB_HANDLER_S *handler);
	
	#endif /* PGSQL_H */

	

	

	

	#ifndef ERROR_H
	#define ERROR_H
	
	#define ERROR_SUCCESS (int)0
	#define ERROR_FAILED (int)1
	
	#define ERROR_CONNECTDB_FAILED (int)2
	#define ERROR_EXECDB_FAILED (int)3
	
	#endif /* ERROR_H */
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