Mysql函数接口

当使用yum安装默认会形成对应的Mysql库，ls /usr/lib64/mysql/，如没有，可到官网 (opens new window)下载对应的版本(编译需要指明 -I./include 和 -L./lib；运行需要export LD_LIBRARY_PATH=./lib)且(将lib路径复制，在/etc/ld.so.conf.d新建xxx.conf，将路径拷贝进去，再执行ldconfig)。

头文件的安装可以使用如下方法

wget https://downloads.mysql.com/archives/get/p/19/file/mysql-connector-c-devel-6.1.11-1.el7.x86_64.rpm

sudo yum localinstall mysql-connector-c-devel-6.1.11-1.el7.x86_64.rpm 

makefile的编写需要如下：

test:test.cc
	g++ -o $@ $^  -std=c++11 -I./incdlue -L/lib64/mysql -lmysqlclient -lpthread  -ldl -lrt

.PHONY:clean
clean:
	rm -rf test

C函数的使用

• 查看版本函数

mysql_get_client_info()

• 使用函数访问数据库步骤

MYSQL *STDCALL mysql_real_connect(MYSQL * mysql, const char *host,
                                    const char *user,
                                    const char *passwd,
                                    const char *db,
                                    unsigned int port,
                                    const char *unix_socket,
                                    unsigned long clientflag);

• 示例代码

#include <iostream>
#include <cstdlib>
#include <mysql/mysql.h>
#include <string>

std::string host = "localhost";
std::string user = "root";
std::string password = "xxx";
std::string dp = "RemoteInnoDB";
const int port = 3306;


int main()
{
    std::cout << "client" << mysql_get_client_info() << std::endl;

    // 创建数据库句柄
    MYSQL *my = mysql_init(nullptr);
    // 连接数据库
    if(mysql_real_connect(my, host.c_str(), user.c_str(), password.c_str(), dp.c_str(), port, nullptr, 0) == nullptr) {
        std::cout << "connect failed" << std::endl;
        exit(1);
    }
    mysql_set_character_set(my, "utf8");
    std::cout << "success" << std::endl;

    //操作数据库
    // std::string inSql = "insert into test values(2, \'王五\')";
    std::string inSql = "select * from test";
    int ret = mysql_query(my, inSql.c_str());
    if(ret == 0) {
        std::cout << "insert success" << std::endl; 
    }else{
        std::cout << inSql << "-> failed" << std::endl; 
    }
    // 查看时对数据解析——针对select
    MYSQL_RES *result = mysql_store_result(my); // 该函数会malloc一块空间保存结果，要手动free(result)

    my_ulonglong row = mysql_num_rows(result);
    unsigned int col = mysql_num_fields(result);

    MYSQL_FIELD * colName = mysql_fetch_fields(result); //获取列明-表头

    for(int i = 0; i < col; i++) {
        std::cout << colName[i].name << "\t";
    }
    std::cout << std::endl;

    for(int i = 0; i < row; i++) {
        MYSQL_ROW oneLine = mysql_fetch_row(result); //返回二级指针,可看成字符串数组
        for(int j = 0; j < col; j++) {
            std::cout << oneLine[j] << "\t";
        }
        std::cout << std::endl;
    }
    free(result);
    mysql_close(my); // 关闭数据库
    return 0;
}