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🗣 Wd提问: c++ mysql

🤖 Ai回答:
I'll help you with C++ and MySQL integration、Here's a comprehensive guide on connecting C++ applications to MySQL databases.

MySQL C++ Connector Setup

Installation

Ubuntu/Debian:
bash
sudo apt-get install libmysqlclient-dev
sudo apt-get install libmysqlcppconn-dev

Windows:
Download MySQL Connector/C++ from Oracle's website
Or use vcpkg: `vcpkg install mysql-connector-cpp`

Basic Connection Example

cpp
include <mysql_driver.h
include <mysql_connection.h
include <cppconn/statement.h
include <cppconn/resultset.h
include <cppconn/exception.h
include <iostream
include <memory

int main() {
try {
// Create MySQL driver instance
sql::mysql::MySQL_Driver *driver = sql::mysql::get_mysql_driver_instance();

// Establish connection
std::unique_ptr<sql::Connection con(driver-connect(
tcp://127.0.0.1:3306, username, password));

// Connect to database
con-setSchema(your_database_name);

// Create statement
std::unique_ptr<sql::Statement stmt(con-createStatement());

// Execute query
std::unique_ptr<sql::ResultSet res(stmt-executeQuery(SELECT * FROM users));

// Process results
while (res-next()) {
std::cout << ID: << res-getInt(id)
<< , Name: << res-getString(name) << std::endl;
}

} catch (sql::SQLException &e) {
std::cout << MySQL Error: << e.what() << std::endl;
std::cout << Error Code: << e.getErrorCode() << std::endl;
std::cout << SQL State: << e.getSQLState() << std::endl;
}

return 0;
}

Prepared Statements Example

cpp
include <mysql_driver.h
include <mysql_connection.h
include <cppconn/prepared_statement.h
include <cppconn/resultset.h
include <iostream

class DatabaseManager {
private:
std::unique_ptr<sql::Connection connection;

public:
bool connect(const std::string& host, const std::string& user,
const std::string& password, const std::string& database) {
try {
sql::mysql::MySQL_Driver *driver = sql::mysql::get_mysql_driver_instance();
connection.reset(driver-connect(host, user, password));
connection-setSchema(database);
return true;
} catch (sql::SQLException &e) {
std::cerr << Connection failed: << e.what() << std::endl;
return false;
}
}

// Insert data using prepared statement
bool insertUser(const std::string& name, const std::string& email) {
try {
std::unique_ptr<sql::PreparedStatement pstmt(
connection-prepareStatement(INSERT INTO users(name, email) VALUES(?, ?)));

pstmt-setString(1, name);
pstmt-setString(2, email);

int rowsAffected = pstmt-executeUpdate();
return rowsAffected 0;
} catch (sql::SQLException &e) {
std::cerr << Insert failed: << e.what() << std::endl;
return false;
}
}

// Select data
void getUsers() {
try {
std::unique_ptr<sql::PreparedStatement pstmt(
connection-prepareStatement(SELECT id, name, email FROM users));

std::unique_ptr<sql::ResultSet res(pstmt-executeQuery());

while (res-next()) {
std::cout << ID: << res-getInt(id)
<< , Name: << res-getString(name)
<< , Email: << res-getString(email) << std::endl;
}
} catch (sql::SQLException &e) {
std::cerr << Query failed: << e.what() << std::endl;
}
}

// Update data
bool updateUser(int id, const std::string& name, const std::string& email) {
try {
std::unique_ptr<sql::PreparedStatement pstmt(
connection-prepareStatement(UPDATE users SET name=?, email=? WHERE id=?));

pstmt-setString(1, name);
pstmt-setString(2, email);
pstmt-setInt(3, id);

int rowsAffected = pstmt-executeUpdate();
return rowsAffected 0;
} catch (sql::SQLException &e) {
std::cerr << Update failed: << e.what() << std::endl;
return false;
}
}

// Delete data
bool deleteUser(int id) {
try {
std::unique_ptr<sql::PreparedStatement pstmt(
connection-prepareStatement(DELETE FROM users WHERE id=?));

pstmt-setInt(1, id);
int rowsAffected = pstmt-executeUpdate();
return rowsAffected 0;
} catch (sql::SQLException &e) {
std::cerr << Delete failed: << e.what() << std::endl;
return false;
}
}
};

int main() {
DatabaseManager db;

if (db.connect(tcp://127.0.0.1:3306, username, password, testdb)) {
std::cout << Connected successfully! << std::endl;

// Insert sample data
db.insertUser(John Doe, john@65.hk);
db.insertUser(Jane Smith, jane@65.hk);

// Display all users
std::cout << \nAll users: << std::endl;
db.getUsers();

// Update a user
db.updateUser(1, John Smith, johnsmith@65.hk);

// Delete a user
db.deleteUser(2);

} else {
std::cout << Failed to connect to database << std::endl;
}

return 0;
}

CMakeLists.txt for Building

cmake
cmake_minimum_required(VERSION 3.10)
project(MySQLCppProject)

set(CMAKE_CXX_STANDARD 14)

Find MySQL Connector/C++
find_package(PkgConfig REQUIRED)
pkg_check_modules(MYSQLCPPCONN REQUIRED mysqlcppconn)

Include directories
include_directories(${MYSQLCPPCONN_INCLUDE_DIRS})

Add executable
add_executable(main main.cpp)

Link libraries
target_link_libraries(main ${MYSQLCPPCONN_LIBRARIES})

Alternative: Using MySQL C API

cpp
include <mysql/mysql.h
include <iostream
include <string

class MySQLWrapper {
private:
MYSQL* connection;

public:
MySQLWrapper() : connection(nullptr) {}

~MySQLWrapper() {
if (connection) {
mysql_close(connection);
}
}

bool connect(const std::string& host, const std::string& user,
const std::string& password, const std::string& database) {
connection = mysql_init(nullptr);
if (!connection) {
std::cerr << mysql_init() failed << std::endl;
return false;
}

if (!mysql_real_connect(connection, host.c_str(), user.c_str(),
password.c_str(), database.c_str(), 0, nullptr, 0)) {
std::cerr << mysql_real_connect() failed: << mysql_error(connection) << std::endl;
return false;
}

return true;
}

bool executeQuery(const std::string& query) {
if (mysql_query(connection, query.c_str())) {
std::cerr << Query failed: << mysql_error(connection) << std::endl;
return false;
}
return true;
}

MYSQL_RES* getResult() {
return mysql_store_result(connection);
}
};

int main() {
MySQLWrapper db;

if (db.connect(localhost, username, password, testdb)) {
std::cout << Connected successfully! << std::endl;

// Execute a query
if (db.executeQuery(SELECT * FROM users)) {
MYSQL_RES* result = db.getResult();
if (result) {
MYSQL_ROW row;
int num_fields = mysql_num_fields(result);

while ((row = mysql_fetch_row(result))) {
for (int i = 0; i < num_fields; i++) {
std::cout << (row[i] ? row[i] : NULL) << ;
}
std::cout << std::endl;
}
mysql_free_result(result);
}
}
}

return 0;
}

Key Points to Remember

1、Error Handling: Always wrap database operations in try-catch blocks
2、Resource Management: Use smart pointers or RAII for automatic cleanup
3、Prepared Statements: Use for security against SQL injection
4、Connection Pooling: Consider implementing for high-performance applications
5、Thread Safety: MySQL connections are not thread-safe by default

Common Issues and Solutions

Linking Errors: Make sure to link against `mysqlcppconn` library
Connection Issues: Verify MySQL server is running and credentials are correct
Memory Leaks: Always free result sets and close connections

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