C++与postgres连接

需要安装的库

jtv/libpqxx: The official C++ client API for PostgreSQL. (github.com)

libpqxx编译安装之前要求安装libpq

sudo apt install libpq-dev

接下来可以利用源代码编译出动态库或者静态库，一下操作默认当前目录为项目目录内。

静态库

./configure --prefix=/home/... #编译出的文件存放目录
make
sudo make install

动态库

mkdir build
cd build
cmake -DBUILD_SHARED_LIBS=ON ..
sudo make install DESTDIR=/home/... #编译出的文件存放目录

使用Cmake构建程序示例。其中要注意的是C++一定要使用17以上的版本，否则编译会报错。

CMakeLists.txt

cmake_minimum_required(VERSION 3.22)
project(template)

set(CMAKE_CXX_STANDARD 17)

set(PostgreSQL_ROOT /var/lib/postgresql/16)
include_directories (${PostgreSQL_INCLUDE_DIR} ${libpqxx_ROOT}/include)


set(libpqxx_ROOT /home/zhang/libpqxx)
link_directories(${PostgreSQL_LIBRARY_DIR} ${libpqxx_ROOT}/lib)

find_package(PostgreSQL REQUIRED)


add_executable(${PROJECT_NAME} main.cpp)
target_link_libraries(${PROJECT_NAME} pqxx ${PostgreSQL_LIBRARIES})

main.c

#include<iostream>
#include"pqxx/pqxx"
int main(){
        std::cout << "hello world" << std::endl;
        std::string conn_string = "hostaddr=127.0.0.1 port=5432 dbname=<database_name> user=<user_name> password=<password>";
        pqxx::connection conn(conn_string);
        pqxx::work txn(conn);
        txn.exec("set search_path = \"<schema_name>\""); //进入schema
        pqxx::result result = txn.exec("SELECT * FROM <table_name>");
        txn.commit();
 // Process results
        for(auto row_it = result.begin(); row_it != result.end(); row_it++){
                std::cout << "id: " << row_it[0].as<int>() << std::endl;
        }
        conn.close();
        return 0;
}