接下来我会详细讲解如何解决C++与mysql连接遇到的常见问题。

C++与mysql连接遇到的问题汇总

安装mysql驱动

在C++中连接mysql需要用到mysql的驱动，因此要先安装mysql驱动。

Windows平台下的mysql驱动安装

• 下载mysql C++ Connector

mysqldownload.csdn.net/pr/d/1575/download/36

• 解压安装

解压后得到一个lib文件夹和一个include文件夹，将lib文件夹中的libmysql.lib（如果是64位系统的话，是libmysql64.lib）复制到C++的lib文件夹下面，将include文件夹中的内容全部复制到C++的include文件夹下面。

注意：lib文件夹和include文件夹中的文件都要复制到正确的位置，否则连接mysql时会出现找不到文件的错误。

Linux平台下的mysql驱动安装

• Ubuntu系统

在终端中输入以下命令：

sudo apt-get install libmysqlcppconn-dev

等待安装完成后，就可以用C++连接mysql了。

• CentOS系统

在终端中输入以下命令：

sudo yum install mysql-connector-c++-devel

等待安装完成后，就可以用C++连接mysql了。

建立连接

在使用C++连接mysql之前，需要先建立连接。

#include <iostream>
#include "mysql_connection.h"
#include "mysql_driver.h"
#include "cppconn/exception.h"
#include "cppconn/resultset.h"
#include "cppconn/statement.h"
using namespace std;
using namespace sql::mysql;

int main() {
    try {
        /* 建立连接 */
        sql::Driver *driver;
        sql::Connection *conn;
        sql::Statement *stmt;
        sql::ResultSet *res;
        driver = get_driver_instance();
        conn = driver->connect("tcp://127.0.0.1:3306", "root", "password");
        stmt = conn->createStatement();
        /* 连接成功后，可以在这里进行操作 */
        stmt->execute("CREATE DATABASE IF NOT EXISTS test");
        stmt->execute("USE test");
        stmt->execute("CREATE TABLE IF NOT EXISTS user ("
                      "id INT NOT NULL AUTO_INCREMENT,"
                      "name VARCHAR(20) NOT NULL,"
                      "age INT NOT NULL,"
                      "PRIMARY KEY (id))");
        cout << "created table user" << endl;
        /* 关闭连接 */
        delete stmt;
        delete conn;
    } catch (sql::SQLException &e) {
        cout << "# ERR: SQLException in " << __FILE__;
        cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;
        cout << "# ERR: " << e.what();
        cout << " (MySQL error code: " << e.getErrorCode();
        cout << ", SQLState: " << e.getSQLState() << " )" << endl;
    }
    return 0;
}

• 使用指定的用户名和密码建立连接：

conn = driver->connect("tcp://127.0.0.1:3306", "root", "password");

这里的127.0.0.1是mysql的IP地址，3306是mysql的端口号，root是用户名，password是密码。如果用户名和密码是正确的，连接将建立成功。

• 连接成功后，可以使用stmt对象进行mysql相关操作。

stmt->execute("CREATE DATABASE IF NOT EXISTS test");

这里创建了一个名为test的数据库。

查询数据

在mysql中查询数据，需要使用到mysql中的SELECT语句。在C++中，可以使用sql::ResultSet对象来保存查询结果。

try {
    /* 建立连接 */
    sql::Driver *driver;
    sql::Connection *conn;
    sql::Statement *stmt;
    sql::ResultSet *res;
    driver = get_driver_instance();
    conn = driver->connect("tcp://127.0.0.1:3306", "root", "password");
    stmt = conn->createStatement();
    /* 查询数据 */
    res = stmt->executeQuery("SELECT * FROM user");
    while (res->next()) {
        cout << "id: " << res->getInt("id") << endl;
        cout << "name: " << res->getString("name") << endl;
        cout << "age: " << res->getInt("age") << endl;
        cout << endl;
    }
    /* 关闭连接 */
    delete res;
    delete stmt;
    delete conn;
} catch (sql::SQLException &e) {
    cout << "# ERR: SQLException in " << __FILE__;
    cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;
    cout << "# ERR: " << e.what();
    cout << " (MySQL error code: " << e.getErrorCode();
    cout << ", SQLState: " << e.getSQLState() << " )" << endl;
}

• 查询语句：

SELECT * FROM user

这里查询了user表中的所有数据。

• 使用res对象保存查询结果：

res = stmt->executeQuery("SELECT * FROM user");

• 遍历结果集并输出：

while (res->next()) {
cout << "id: " << res->getInt("id") << endl;
cout << "name: " << res->getString("name") << endl;
cout << "age: " << res->getInt("age") << endl;
cout << endl;
}

这里使用了res->getInt("id")、res->getString("name")和res->getInt("age")来获取查询结果中的数据。

以上就是使用C++连接mysql时遇到问题的解决方案，希望能对你有所帮助。

示例1：

• 首先，我们需要在mysql中创建一个database和一个table，用来存储我们的数据。

CREATE DATABASE IF NOT EXISTS test;
USE test;
CREATE TABLE IF NOT EXISTS student (
id INT NOT NULL AUTO_INCREMENT,
name VARCHAR(20) NOT NULL,
age INT NOT NULL,
PRIMARY KEY (id)
);
INSERT INTO student (name, age) VALUES ("Tom", 18);
INSERT INTO student (name, age) VALUES ("Jerry", 19);

• 然后，在C++中连接mysql并查询student表中的所有数据。

cpp
try {
/* 建立连接 */
sql::Driver* driver;
sql::Connection* conn;
sql::Statement* stmt;
sql::ResultSet* res;
driver = get_driver_instance();
conn = driver->connect("tcp://127.0.0.1:3306", "root", "password");
stmt = conn->createStatement();
/* 查询数据 */
res = stmt->executeQuery("SELECT * FROM student");
while (res->next()) {
cout << "id: " << res->getInt("id") << endl;
cout << "name: " << res->getString("name") << endl;
cout << "age: " << res->getInt("age") << endl;
cout << endl;
}
/* 关闭连接 */
delete res;
delete stmt;
delete conn;
}
catch (sql::SQLException& e) {
cout << "# ERR: SQLException in " << __FILE__;
cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;
cout << "# ERR: " << e.what();
cout << " (MySQL error code: " << e.getErrorCode();
cout << ", SQLState: " << e.getSQLState() << " )" << endl;
}

• 编译运行，输出结果：

```
id: 1
name: Tom
age: 18

id: 2
name: Jerry
age: 19
```

示例2：

• 我们还可以使用C++向mysql中插入一条数据。

cpp
try {
/* 建立连接 */
sql::Driver* driver;
sql::Connection* conn;
sql::Statement* stmt;
driver = get_driver_instance();
conn = driver->connect("tcp://127.0.0.1:3306", "root", "password");
stmt = conn->createStatement();
/* 插入数据 */
stmt->execute("INSERT INTO student (name, age) VALUES ('Lisa', 20)");
/* 查询数据 */
sql::ResultSet* res = stmt->executeQuery("SELECT * FROM student");
while (res->next()) {
cout << "id: " << res->getInt("id") << endl;
cout << "name: " << res->getString("name") << endl;
cout << "age: " << res->getInt("age") << endl;
cout << endl;
}
/* 关闭连接 */
delete res;
delete stmt;
delete conn;
}
catch (sql::SQLException& e) {
cout << "# ERR: SQLException in " << __FILE__;
cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl;
cout << "# ERR: " << e.what();
cout << " (MySQL error code: " << e.getErrorCode();
cout << ", SQLState: " << e.getSQLState() << " )" << endl;
}

• 编译运行，输出结果：

```
id: 1
name: Tom
age: 18

id: 2
name: Jerry
age: 19

id: 3
name: Lisa
age: 20
```