Linux Mysql C++ API 封装以及使用方法

头文件

#ifndef _MYMYSQL_H #define _MYMYSQL_H #include <string> #include "mysql.h" using namespace std; class MyMysql { protected: bool m_hasRead = false; //执行exec后，是否已调用过mysql_read int m_curReadValueIndex = -1; //执行mysql_read后，下次取第几行的数据 int m_affected_rows = -1; //exec影响的行数 // 存储读取数据 string **m_execResult; int m_rowCount; int m_colCount; MyMysql(); public: static MyMysql *m_pInstance; // 连接事例 MYSQL *m_dbHandle = nullptr; static MyMysql *NewInstance(); // mysql连接 bool connectToDatabase(const char *hostName, const char *user, const char *passwd, const char *dbname); bool exec(const string &s); //执行SQL语句，末尾不需要加分号 bool next(); string values(int index); // 获取更新行列数 int rowCount(); int columnCount(); // 数据读取 void mysql_read(); int databaseClose(); public: ~MyMysql(); }; #endif

源文件

#include "MyMysql.h" #include <cstring> #include <iostream> using namespace std; MyMysql *MyMysql::m_pInstance = new MyMysql(); MyMysql::MyMysql() { this->m_dbHandle = mysql_init(NULL); } MyMysql::~MyMysql() { mysql_close(this->m_dbHandle); } MyMysql *MyMysql::NewInstance() { return m_pInstance; } bool MyMysql::connectToDatabase(const char *hostName, const char *user, const char *passwd, const char *dbname) { if (mysql_real_connect(this->m_dbHandle, hostName, user, passwd, dbname, 0, NULL, 0)) { //cout << "连接成功" << endl; // 设置编码 mysql_query(m_dbHandle, "set names utf8"); return true; } return false; } bool MyMysql::exec(const string &s) { m_hasRead = false; m_affected_rows = -1; m_curReadValueIndex = -1; return (mysql_query(this->m_dbHandle, s.c_str()) == 0); } bool MyMysql::next() { if (!m_hasRead) { mysql_read(); m_hasRead = true; m_affected_rows = mysql_affected_rows(this->m_dbHandle); } return (++m_curReadValueIndex < m_affected_rows); } string MyMysql::values(int index) { string ret; if (m_curReadValueIndex < m_affected_rows) { ret = this->m_execResult[m_curReadValueIndex][index]; } return ret; } int MyMysql::rowCount() { if (m_affected_rows == -1) { mysql_read(); m_hasRead = true; m_affected_rows = mysql_affected_rows(this->m_dbHandle); } return m_affected_rows; } int MyMysql::columnCount() { return m_colCount; } void MyMysql::mysql_read() { // 释放数据 if (this->m_rowCount != 0) { for (int i = 0; i < this->m_rowCount; i++) { delete[] this->m_execResult[i]; } delete[] this->m_execResult; } MYSQL_RES *result = mysql_store_result(this->m_dbHandle); if (result != nullptr) { MYSQL_ROW row; int cow_lenth = result->field_count; int row_lenth = result->row_count; // 数据存储 this->m_execResult = new string *[row_lenth]; for (int i = 0; i < row_lenth; i++) { this->m_execResult[i] = new string[cow_lenth]; } // 行 this->m_rowCount = row_lenth; // 列 this->m_colCount = cow_lenth; for (int i = 0; i < row_lenth; i++) { row = mysql_fetch_row(result); for (int j = 0; j < cow_lenth; j++) { //若数据库中该字段为空值，那么这里要判断一下row[j]是否为空，否则导致段错误 if (row[j]) { this->m_execResult[i][j] = row[j]; } else { this->m_execResult[i][j] = ""; } } } // 释放数据 mysql_free_result(result); } } int MyMysql::databaseClose() { mysql_close(m_dbHandle); return 0; }

CMake链接方法

include_directories( /usr/include/mysql ) link_directories( /usr/lib/x86_64-linux-gnu ) target_link_libraries(target libmysqlclient.so)

示例代码

#include "mysql.h" #include <stdio.h> #include <string.h> #include <string> #include <iostream> #include <cstring> #include "MyMysql.h" #include <iostream> using namespace std; int main() { MyMysql* pInstall = MyMysql::NewInstance(); pInstall->connectToDatabase("IP地址","用户名", "密码", "数据库名"); pInstall->exec("select * from 表名"); cout << "行数:" << pInstall->rowCount() << endl; cout << "列数:" << pInstall->columnCount() << endl; while(pInstall->next()) { for(int i = 0;i < pInstall->columnCount();++i) { cout << pInstall->value(i) << " "; } cout << endl; } return 0; }