Linux下安装PostgreSQL自行百度安装，废话不说，直接贴代码
头文件： Postgres.h
#ifndef __POSTGRES__ #define __POSTGRES__ #include <iostream> #include <string> #include "pqxx/pqxx" #include <map> using namespace std; using namespace pqxx; typedef std::map<int, std::map<std::string, std::string> > map_Result; class PGResultOper; class CPostgres { public: CPostgres(); ~CPostgres(); // 建立连接 [10/21/2019 none] bool DBConnect(string connstring = ""); // 断开连接 [10/21/2019 none] void DisDBConnect(); // 执行增删改sql语句 [10/21/2019 none] bool ExecSql(const std::string& sql, bool bCommit = true); //执行查询sql语句 [10/21/2019 none] PGResultOper* Execute_Query(const std::string& sql); private: // 重连 [10/21/2019 none] bool Is_Connect(); private: PGResultOper* m_pResult_Oper; //结果集类 pqxx::connection* m_dbConn; pqxx::result m_res; std::string m_strConnInfo; std::string m_err_str; bool m_bConnected; }; // 结果集类 class PGResultOper { public: PGResultOper(); ~PGResultOper(); public: // 根据字段名字取值 [10/22/2019 none] const char* Field(const char* col_name); // 根据索引号字取值 [10/22/2019 none] const char* Field(unsigned int col_index); // 根据字段名字取值 [10/22/2019 none] const char* Get(const char* col_name); // 根据索引号字段名字取值 [10/22/2019 none] const char* GetFieldName(unsigned int col_index); // 结果集大小(行数) [10/22/2019 none] unsigned int Row_Num(); // 结果集列大小 [10/22/2019 none] unsigned int Column_Num(); // 结果集行号,从1开始 [10/22/2019 none] unsigned int Row_Id(); // 判断结果集是否读完 [10/22/2019 none] bool IsEOF(); // 读取下一行 [10/22/2019 none] bool Next(); //根据字段名字取值, 运算符重载 const char* operator[](const char* col_name); // 遍历结果集操作符 [10/22/2019 none] bool operator++(int); // 存储查询结果集 [10/22/2019 none] void Set_map_res(const map_Result& results, const pqxx::result& res); private: bool m_bItor_first; map_Result::iterator res_itor; map_Result m_mapRes; pqxx::result m_pq_res; }; #endif // !__POSTGRES__实现类：Postgres.cpp
#include "Postgres.h" CPostgres::CPostgres() { m_strConnInfo = ""; m_pResult_Oper = new PGResultOper; m_dbConn = NULL; m_err_str = ""; m_bConnected = false; } CPostgres::~CPostgres() { if (m_pResult_Oper != nullptr) { delete m_pResult_Oper; } } // 建立连接 [10/21/2019 none] bool CPostgres::DBConnect(std::string strConnInfo) { m_strConnInfo = strConnInfo; bool bret = true; try { if (m_strConnInfo.empty()) { m_err_str = "connect string is empty!"; return false; } try { m_dbConn = new pqxx::connection(m_strConnInfo.c_str()); if (m_dbConn == NULL) { m_err_str = "db connection ptr is null."; return false; } } catch (const std::exception &e) { m_err_str = "db connect unknown exception."; return false; } if (m_dbConn->is_open()) { m_err_str = "Opened database successfully, dbname: " + std::string(m_dbConn->dbname()); } else { bret = false; DisDBConnect(); } } catch (const std::exception &e) { m_err_str = e.what(); bret = false; DisDBConnect(); } catch (...) { m_err_str = "unknown exception."; bret = false; DisDBConnect(); } return bret; } // 断开连接 [10/21/2019 none] void CPostgres::DisDBConnect() { m_err_str.clear(); if (m_dbConn == NULL) { m_err_str = "db connection ptr is null."; return; } m_dbConn->disconnect(); if (m_dbConn != NULL) { delete m_dbConn; m_dbConn = NULL; } } // 重连 [10/21/2019 none] bool CPostgres::Is_Connect() { bool bret = false; m_err_str.clear(); try { if (m_dbConn == nullptr) { m_err_str = "db connection ptr is null."; return false; } if (!m_dbConn->is_open()) { m_bConnected = false; DisDBConnect(); bret = DBConnect(m_strConnInfo); } else { bret = true; m_bConnected = true; } } catch (...) { m_err_str = "unknown exception."; m_bConnected = false; bret = false; DisDBConnect(); } printf("Reconnect postgresql success \n"); return bret; } // 提交 [10/21/2019 none] bool CPostgres::ExecSql(const std::string& sql, bool bCommit) { bool bret = true; m_err_str.clear(); try { if (m_dbConn == nullptr) { m_err_str = "db connection ptr is null."; return false; } work worker(*m_dbConn); worker.exec(sql); worker.commit(); } catch (const pqxx::pqxx_exception &pe) { m_err_str = pe.base().what(); bret = false; } catch (const std::exception &e) { m_err_str = e.what(); bret = false; } catch (...) { m_err_str = "unknown exception."; bret = false; } return bret; } //执行查询sql语句 [10/21/2019 none] PGResultOper* CPostgres::Execute_Query(const std::string& sql) { m_err_str.clear(); try { if (m_dbConn == NULL) { m_err_str = "db connection ptr is null."; return nullptr; } nontransaction nts(*m_dbConn); /* Create a non-transactional object. */ pqxx::result res = nts.exec(sql); /* Execute SQL query */ m_res = res; map_Result results; //查询结果集 for (unsigned int row = 0; row < res.size(); row++) { std::map<std::string, std::string> pairs; //map[行, map[字段名, 值] ] for (unsigned int col = 0; col < res.columns(); col++) { //printf("==map===clounm:%s, value:%s\n", res[row][col].name(), res[row][col].c_str()); pairs.insert(std::make_pair(res[row][col].name(), res[row][col].c_str())); results[row] = pairs; } } m_pResult_Oper->Set_map_res(results, m_res); //存储查询结果集 } catch (const pqxx::pqxx_exception &pe) { m_err_str = pe.base().what(); return nullptr; } catch (const std::exception &e) { m_err_str = e.what(); return nullptr; } catch (...) { m_err_str = "unknown exception."; return nullptr; } return m_pResult_Oper; } /* --------------------------------------------------------------------------------------------- * * PGResultOper * --------------------------------------------------------------------------------------------- */ PGResultOper::PGResultOper() { m_mapRes.clear(); res_itor = m_mapRes.begin(); m_bItor_first = true; } PGResultOper::~PGResultOper() { m_mapRes.clear(); res_itor = m_mapRes.begin(); } // 根据字段名字取值 [10/22/2019 none] const char * PGResultOper::Field(const char * col_name) { if (res_itor == m_mapRes.end() || m_mapRes.empty()) { return ""; } return res_itor->second[col_name].c_str(); } // 根据索引号字取值 [10/22/2019 none] const char * PGResultOper::Field(unsigned int col_index) { if (col_index >= res_itor->second.size() || m_mapRes.empty()) { return ""; } return m_pq_res[Row_Id()][col_index].c_str(); } // 根据字段名字取值 [10/22/2019 none] const char * PGResultOper::Get(const char * col_name) { if (res_itor == m_mapRes.end() || m_mapRes.empty()) { return ""; } return res_itor->second[col_name].c_str(); } // 根据索引号字段名字取值 [10/22/2019 none] const char * PGResultOper::GetFieldName(unsigned int col_index) { if (col_index >= res_itor->second.size() || m_mapRes.empty()) { return ""; } return m_pq_res[Row_Id()][col_index].name(); } // 结果集大小(行数) [10/22/2019 none] unsigned int PGResultOper::Row_Num() { return (unsigned int)m_mapRes.size(); } // 结果集列大小 [10/22/2019 none] unsigned int PGResultOper::Column_Num() { if (m_mapRes.empty()) { return 0; } return res_itor->second.size(); } // 判断结果集是否读完 [10/22/2019 none] bool PGResultOper::IsEOF() { if (m_mapRes.empty()) { return true; } return (res_itor == m_mapRes.end()); } // 读取下一行 [10/22/2019 none] bool PGResultOper::Next() { if (m_mapRes.empty()) { return false; } if (res_itor != m_mapRes.end()) { res_itor++; return true; } return false; } const char * PGResultOper::operator[](const char * col_name) { return Get(col_name); } // 遍历结果集操作符 [10/22/2019 none] bool PGResultOper::operator++(int) { return Next(); } void PGResultOper::Set_map_res(const map_Result& results, const pqxx::result& res) { m_mapRes = results; res_itor = m_mapRes.begin(); m_pq_res = res; m_bItor_first = true; } // 结果集行号,从1开始 [10/22/2019 none] unsigned int PGResultOper::Row_Id() { if (res_itor == m_mapRes.end()) { return 0; } return res_itor->first; }main.cpp
#include <iostream> #include <pqxx/pqxx> #include "Postgres.h" #include <string.h> using namespace std; using namespace pqxx; // g++ *.cpp -std=c++11 -lpqxx -lpq -I/usr/local/include -o main -w int main(int argc, char* argv[]) { CPostgres *postgres = new CPostgres(); //host=172.20.32.241 dbname=dnps user=dnps password=dnps port=5432 connect_timeout=5 if (!postgres->DBConnect("dbname=dnps user=dnps password=dnps hostaddr=172.20.32.241 port=5432")) { printf("postgresql connect failed\n"); return -1; } printf("postgresql connect success\n"); char szSql[256] = { 0 }; memset(szSql, 0, 256); sprintf(szSql, "insert into testpg (xh, sbbh, sbmc) values ('%s', '610502', '东长安街1号')", "11"); // insert printf("测试插入操作\n"); for (int i = 0; i < 4; ++i) { if(!postgres->ExecSql(szSql)) //insert into "testpg"("xh", "sbbh", "sbmc") values ('1', '1', '1') { printf("Insert data failed\n"); continue; } printf("Insert data success \n"); } //测试查询操作 printf("测试查询操作\n"); PGResultOper* results = NULL; results = postgres->Execute_Query("select * from testpg where sbbh='610502'"); if (results == nullptr) { printf("querry data failed\n"); return -1; } while (!results->IsEOF()) { string str_name = results->GetFieldName(1); string str_xh = results->Field("xh"); string str_sbbh = results->Field("sbbh"); string str_sbmc = results->Field("sbmc"); int num = atoi(results->Field("xh")); printf("str_name:%s, XH:%s, SBBH:%s, SBMC:%s, num:%d\n", str_name.c_str(), str_xh.c_str(), str_sbbh.c_str(), str_sbmc.c_str(), num); results->Next(); } //测试更新操作 printf("测试更新操作\n"); if (!postgres->ExecSql("update testpg set xh = '101' where xh = '22';", true)) { printf("Update data failed\n"); } printf("Update data success \n"); //测试更新后查询操作 printf("测试更新后查询操作\n"); results = NULL; results = postgres->Execute_Query("select * from testpg where sbbh='610502'"); if (results == nullptr) { printf("querry data failed\n"); return -1; } while (!results->IsEOF()) { string str_name = results->GetFieldName(1); string str_xh = results->Field("xh"); string str_sbbh = results->Field("sbbh"); string str_sbmc = results->Field("sbmc"); int num = atoi(results->Field("xh")); printf("str_name:%s, XH:%s, SBBH:%s, SBMC:%s, num:%d\n", str_name.c_str(), str_xh.c_str(), str_sbbh.c_str(), str_sbmc.c_str(), num); results->Next(); } postgres->DisDBConnect(); delete postgres; return 0; }编译运行: g++ *.cpp -std=c++11 -lpqxx -lpq -I/usr/local/include -o main -w
