Rust Cassandra数据库驱动cassandra-cpp的使用指南

以下是cassandra-cpp驱动的基本使用示例：

1. 连接到Cassandra集群

use cassandra_cpp::*;

fn main() -> Result<(), CassError> {
    // 创建集群对象并配置
    let cluster = Cluster::default();
    cluster.set_contact_points("127.0.0.1")?;
    
    // 连接到集群
    let session = cluster.connect()?;
    
    // 执行简单查询
    let result = session.execute("SELECT keyspace_name FROM system_schema.keyspaces;")?;
    
    // 处理结果
    for row in result.iter() {
        let keyspace_name: String = row.get_by_name("keyspace_name")?;
        println!("Keyspace: {}", keyspace_name);
    }
    
    Ok(())
}

2. 使用预编译语句

use cassandra_cpp::*;

fn insert_data(session: &Session) -> Result<(), CassError> {
    // 准备预编译语句
    let query = "INSERT INTO example.users (id, name, email) VALUES (?, ?, ?)";
    let statement = session.statement(query);
    
    // 绑定参数并执行
    statement.bind(0, 1)?;              // id
    statement.bind(1, "John Doe")?;     // name
    statement.bind(2, "john@example.com")?; // email
    
    session.execute(&statement).wait()?;
    Ok(())
}

完整示例代码

下面是一个完整的Cassandra CRUD操作示例：

use cassandra_cpp::*;
use futures::executor::block_on;

async fn cassandra_example() -> Result<(), CassError> {
    // 1. 创建集群连接
    let cluster = Cluster::default();
    cluster.set_contact_points("127.0.0.1")?;
    cluster.set_num_threads_io(4)?;
    let session = cluster.connect()?;

    // 2. 创建keyspace和表
    session.execute(
        "CREATE KEYSPACE IF NOT EXISTS example WITH replication = {
            'class': 'SimpleStrategy', 
            'replication_factor': '1'
        }"
    ).wait()?;

    session.execute(
        "CREATE TABLE IF NOT EXISTS example.users (
            id int PRIMARY KEY,
            name text,
            email text
        )"
    ).wait()?;

    // 3. 插入数据
    let insert_query = "INSERT INTO example.users (id, name, email) VALUES (?, ?, ?)";
    let mut statement = session.statement(insert_query);
    
    statement.bind(0, 1)?;
    statement.bind(1, "Alice")?;
    statement.bind(2, "alice@example.com")?;
    session.execute(&statement).wait()?;

    // 4. 批量插入
    let mut batch = Batch::new(BatchType::LOGGED);
    for i in 2..=5 {
        let mut stmt = session.statement(insert_query);
        stmt.bind(0, i)?;
        stmt.bind(1, format!("User {}", i))?;
        stmt.bind(2, format!("user{}@example.com", i))?;
        batch.add_statement(&stmt)?;
    }
    session.execute_batch(&batch).wait()?;

    // 5. 查询数据
    let result = session.execute("SELECT * FROM example.users").wait()?;
    for row in result.iter() {
        let id: i32 = row.get(0)?;
        let name: String = row.get(1)?;
        let email: String = row.get(2)?;
        println!("ID: {}, Name: {}, Email: {}", id, name, email);
    }

    // 6. 更新数据
    let update_query = "UPDATE example.users SET email = ? WHERE id = ?";
    let mut update_stmt = session.statement(update_query);
    update_stmt.bind(0, "new.alice@example.com")?;
    update_stmt.bind(1, 1)?;
    session.execute(&update_stmt).wait()?;

    // 7. 删除数据
    let delete_query = "DELETE FROM example.users WHERE id = ?";
    let mut delete_stmt = session.statement(delete_query);
    delete_stmt.bind(0, 5)?;
    session.execute(&delete_stmt).wait()?;

    Ok(())
}

fn main() -> Result<(), CassError> {
    block_on(cassandra_example())
}

示例说明

1. 首先创建Cluster对象并配置连接参数
2. 连接到Cassandra集群并创建Session
3. 创建keyspace和表结构（如果不存在）
4. 使用预编译语句插入单条数据
5. 使用批量操作插入多条数据
6. 查询并打印所有用户数据
7. 更新特定用户的邮箱
8. 删除指定ID的用户

这个示例展示了cassandra-cpp驱动的基本CRUD操作，包括连接管理、数据插入、查询、更新和删除等常见操作。