使用 Rust 语言连接 KWDB

Rust 是强调性能、安全性和并发性的通用编程语言。Cargo 是 Rust 的官方包管理工具和构建系统，帮助开发者管理 Rust 项目的依赖关系、编译代码、生成文档以及发布包。

KWDB 支持用户使用 Rust 语言连接数据库，并执行创建、插入和查询操作。本示例演示了如何通过 Cargo 连接和使用 KWDB。

前提条件

安装 Rustopen in new window。
安装和运行 KWDB 数据库、配置数据库认证方式、创建数据库。
创建具有表级别及以上操作权限的用户。

配置示例

创建新的 Rust 项目并进入项目目录。

cargo new kaiwudb-demo-rs
cd kaiwudb-demo-rs

打开 src/main.rs 文件，并将以下代码粘贴到文件中：

use chrono::{DateTime, Utc};
use openssl::{
    error::ErrorStack,
    ssl::{SslConnector, SslFiletype, SslMethod},
};
use postgres::{Client, Error as PgError, NoTls};
use postgres_openssl::MakeTlsConnector;
use std::env;

fn load_ssl() -> Result<MakeTlsConnector, ErrorStack> {
    let mut builder = SslConnector::builder(SslMethod::tls())?;
    builder.set_ca_file("./certs/ca.crt")?;
    builder.set_certificate_file("../../certs/client.root.crt", SslFiletype::PEM)?;
    builder.set_private_key_file("../../certs/client.root.key", SslFiletype::PEM)?;
    return Ok(MakeTlsConnector::new(builder.build()));
}

macro_rules! rs_count_print {
    ($sql:expr, $n:expr) => {
        println!("{}\n({} rows)", $sql, $n);
    };
}

fn main() -> Result<(), PgError> {
    let conn_str = format!(
        "host={} port={} user={}",
        env::var("DBHOST").unwrap_or(String::from("localhost")),
        env::var("DBPORT")
            .unwrap_or(String::from("26257"))
            .parse::<u16>()
            .unwrap(),
        env::var("DBUSER").unwrap_or(String::from("root"))
    );
    let databases = [["", "db_shig"], ["TS", "ts_shig"]];
    // 创建客户端对象
    let pg_client = if "true" == (env::var("NOSSL").unwrap_or(String::from("false"))) {
        Client::connect(&conn_str, NoTls)
    } else {
        Client::connect(&conn_str, load_ssl().unwrap())
    };
    let mut client = pg_client.unwrap();
    // 初始化数据库
    for db in [["", "db_shig"], ["TS", "ts_shig"]] {
        client.execute(format!("DROP DATABASE IF EXISTS {}", &db[1]).as_str(), &[])?;
        println!("DROP DATABASE {} SUCCESS!", &db[1]);
    }
    // 创建数据库
    for db in databases {
        client.execute(
            format!("CREATE {} DATABASE {}", &db[0], &db[1]).as_str(),
            &[],
        )?;
        println!("DROP {} DATABASE {} SUCCESS!", &db[0], &db[1]);
    }
    for db in [["", "db_shig"], ["TS", "ts_shig"]] {
        client.execute(format!("DROP DATABASE IF EXISTS {}", &db[1]).as_str(), &[])?;
        println!("DROP DATABASE {} SUCCESS!", &db[1]);
    }
    // 创建数据库
    for db in [["", "db_shig"], ["TS", "ts_shig"]] {
        client.execute(
            format!("CREATE {} DATABASE {}", &db[0], &db[1]).as_str(),
            &[],
        )?;
        println!("DROP {} DATABASE {} SUCCESS!", &db[0], &db[1]);
    }
    // 创建表
    rs_count_print!(
        "CREATE TABLE ts_shig.t_electmeter",
        client.execute(
            "CREATE TABLE ts_shig.t_electmeter (
        k_timestamp timestamp NOT NULL,
        elect_name char(63) NOT NULL,
        vol_a double NOT NULL,
        cur_a double NOT NULL,
        powerf_a double) ATTRIBUTES (machine_code varchar(64) NOT NULL) 
                        PRIMARY TAGS(machine_code) 
                        retentions 3d activetime 1h 
                        partition interval 1d;",
            &[],
        )?
    );
    rs_count_print!(
        "CREATE TABLE db_shig.factory",
        client.execute(
            "CREATE TABLE db_shig.factory (
        id int2 PRIMARY KEY,
        name varchar(8),
        sub_comp_id int2 NOT NULL
    )",
            &[],
        )?
    );
    // 插入
    rs_count_print!(
        "INSERT INTO ts_shig.t_electmeter",
        client.execute(
            "INSERT INTO ts_shig.t_electmeter (
        k_timestamp, elect_name, vol_a, cur_a, powerf_a, machine_code) 
        VALUES (now(), $1, $2, $3, $4, $5)",
            &[&"NULL", &299.4_f64, &0.01_f64, &0.01_f64, &"1_2"],
        )?
    );
    rs_count_print!(
        "INSERT INTO ts_shig.t_electmeter",
        client.execute(
            "INSERT INTO ts_shig.t_electmeter (
        k_timestamp, elect_name, vol_a, cur_a, powerf_a, machine_code) 
        VALUES (now(), $1, $2, $3, $4, $5)",
            &[&"a017", &199.4_f64, &0.11_f64, &0.21_f64, &"3_2"],
        )?
    );
    rs_count_print!(
        "INSERT INTO db_shig.factory",
        client.execute(
            "INSERT INTO db_shig.factory (
        id, name, sub_comp_id) VALUES ($1, $2, $3)",
            &[&1_i16, &"12,22FAC", &1_i16],
        )?
    );
    client.batch_execute(
        "INSERT INTO db_shig.factory 
        VALUES (2,'1_1FAC',2),(3,'3_3FAC',3),(99,'99_99FAC',5)",
    )?;
    // 查询
    println!("SELECT ts_shig.t_electmeter");
    client
        .query("SELECT * FROM ts_shig.t_electmeter", &[])
        .map(|rows| {
            for row in &rows {
                let k_timestamp: DateTime<Utc> = row.get("k_timestamp");
                let elect_name: String = row.get("elect_name");
                let vol_a: f64 = row.get("vol_a");
                let cur_a: f64 = row.get("cur_a");
                let powerf_a: f64 = row.get("powerf_a");
                let machine_code: String = row.get("machine_code");
                println!(
                    "{},{},{},{},{},{}",
                    k_timestamp, elect_name, vol_a, cur_a, powerf_a, machine_code
                );
            }
            println!("({} rows)", rows.len());
        })?;
    println!("SELECT db_shig.factory");
    client
        .query(
            "SELECT name, sub_comp_id FROM db_shig.factory WHERE id=$1",
            &[&1_i16],
        )
        .map(|rows| {
            for row in &rows {
                let name: String = row.get("name");
                let sub_comp_id: i16 = row.get("sub_comp_id");
                println!("{},{}", name, sub_comp_id);
            }
            println!("({} rows)", rows.len());
        })?;
    // 修改
    rs_count_print!(
        "UPDATE db_shig.factory",
        client.execute(
            "UPDATE db_shig.factory SET name=$1 WHERE id=$2",
            &[&"99UPDATE", &99_i16],
        )?
    );
    // 删除
    rs_count_print!(
        "DELETE FROM db_shig.factory",
        client.execute("DELETE FROM db_shig.factory WHERE id=$1", &[&3_i16],)?
    );
    // 删除数据表
    client.batch_execute("DROP TABLE db_shig.factory")?;
    rs_count_print!(
        "DROP TABLE ts_shig.t_electmeter",
        client.execute("DROP TABLE ts_shig.t_electmeter", &[],)?
    );
    // 删除数据库
    for db in &databases {
        let drop_sql = format!("DROP DATABASE {}", &db[1]);
        rs_count_print!(&drop_sql, client.execute(&drop_sql, &[])?);
    }
    Ok(())
}

在项目根目录下找到 Cargo.toml 文件，添加以下依赖：

[package]
name = "kaiwudb-demo-rs"
version = "0.1.0"
edition = "2021"

[dependencies]
chrono = "0.4.38"
openssl = "0.10.66"
postgres = { version = "0.19.8", features = ["with-chrono-0_4"] }
postgres-openssl = "0.5.0"

在项目根目录中，编译和运行项目：
```
cargo build
cargo run
```

# 使用 Rust 语言连接 KWDB

# 前提条件

# 配置示例

使用 Rust 语言连接 KWDB

前提条件

配置示例