How to develop a simple file synchronization function using MySQL and C++

How to use MySQL and C to develop a simple file synchronization function

With the rapid development of the Internet, sharing and synchronizing files on different devices has become more and more common. In order to achieve such a function, we can use MySQL as a metadata storage and management tool for file synchronization, and use the C programming language to perform file reading, writing and synchronization operations. This article will introduce how to use MySQL and C to develop a simple file synchronization function, and provide specific code examples.

Step 1: Create database and table structure

First, we need to create a database to store file synchronization metadata. Open the MySQL command line or use a visual tool to create a database named "file_sync_db":

CREATE DATABASE file_sync_db;

Next, create a table named "files" in this database to store the metadata of the file Information:

USE file_sync_db;

CREATE TABLE files (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    path VARCHAR(255) NOT NULL,
    size INT NOT NULL,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

The structure of this table includes id (auto-incrementing primary key), name (file name), path (file path), size (file size) and updated_at (update time).

Step 2: Write C code

Next, we use C to write code, connect to the MySQL database, and implement file reading, writing and synchronization operations.

First, we need to introduce the C connection library of MySQL. Add the following statement in the C code:

#include <mysql_driver.h>
#include <mysql_connection.h>
#include <cppconn/driver.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>

Then, we need to define some constants for connecting to the MySQL database:

const std::string DB_HOST = "localhost";
const std::string DB_USER = "root";
const std::string DB_PASS = "password";
const std::string DB_NAME = "file_sync_db";

Next, we can write code to connect to the MySQL database:

sql::mysql::MySQL_Driver *driver;
sql::Connection *con;
sql::Statement *stmt;

// 连接到MySQL数据库
driver = sql::mysql::get_mysql_driver_instance();
con = driver->connect(DB_HOST, DB_USER, DB_PASS);
con->setSchema(DB_NAME);
stmt = con->createStatement();

After the connection is successful, we can write some functions to implement file reading, writing and synchronization functions. Here are some sample functions:

1. Add a file to the database

void addFile(const std::string& name, const std::string& path, int size) {
    // 构造插入语句
    sql::PreparedStatement *prep_stmt;
    prep_stmt = con->prepareStatement("INSERT INTO files (name, path, size) VALUES (?, ?, ?)");
    prep_stmt->setString(1, name);
    prep_stmt->setString(2, path);
    prep_stmt->setInt(3, size);
    prep_stmt->execute();

    delete prep_stmt;
}

2. Get all files from the database

std::vector<std::tuple<int, std::string, std::string, int>> getAllFiles() {
    // 执行查询语句
    sql::ResultSet *res;
    res = stmt->executeQuery("SELECT * FROM files");

    std::vector<std::tuple<int, std::string, std::string, int>> files;
    while (res->next()) {
        int id = res->getInt("id");
        std::string name = res->getString("name");
        std::string path = res->getString("path");
        int size = res->getInt("size");

        files.push_back(std::make_tuple(id, name, path, size));
    }

    delete res;

    return files;
}

3. Delete a file in the database

void deleteFile(int id) {
    // 构造删除语句
    sql::PreparedStatement *prep_stmt;
    prep_stmt = con->prepareStatement("DELETE FROM files WHERE id = ?");
    prep_stmt->setInt(1, id);
    prep_stmt->execute();

    delete prep_stmt;
}

The above are just some example functions, you can add more functions according to actual needs.

Step 3: Use the written C code to implement file synchronization

Through the above steps, we have written C code that can connect to the MySQL database and implemented the reading and writing of some files. Sync function. You can write your own business logic to achieve file synchronization according to specific needs.

The following is a simple example of file synchronization, adding files to the database and performing file synchronization operations:

int main() {
    // 连接到数据库
    sql::mysql::MySQL_Driver *driver;
    sql::Connection *con;
    sql::Statement *stmt;

    driver = sql::mysql::get_mysql_driver_instance();
    con = driver->connect(DB_HOST, DB_USER, DB_PASS);
    con->setSchema(DB_NAME);
    stmt = con->createStatement();

    // 添加文件到数据库
    addFile("example.txt", "/path/to/example.txt", 1024);

    // 获取所有文件
    std::vector<std::tuple<int, std::string, std::string, int>> files = getAllFiles();

    // 打印所有文件
    for (auto file : files) {
        std::cout << "ID: " << std::get<0>(file) << ", Name: " << std::get<1>(file)
                  << ", Path: " << std::get<2>(file) << ", Size: " << std::get<3>(file) << std::endl;
    }

    // 删除文件
    deleteFile(1);

    delete stmt;
    delete con;

    return 0;
}

Through the above code, we realize the adding, reading and file synchronization of files. Delete operations, and file synchronization can be performed through the MySQL database.

Summary

This article introduces how to use MySQL and C to develop a simple file synchronization function. By using MySQL as a metadata storage and management tool for file synchronization, and combining it with the C programming language to perform file reading, writing, and synchronization operations, we can implement functions such as adding, deleting, and synchronizing files. The above code example is a simple file synchronization operation. You can modify and expand it according to actual needs to implement more complex file synchronization functions.

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