示例代码来自https://github.com/easynet-cn/batata，本人的一个想兼容nacos（https://github.com/alibaba/nacos）rust项目。其中数据entity是使用sea-orm cli生成，具体可以参考文档https://www.sea-ql.org/SeaORM/docs/next/generate-entity/sea-orm-cli/

构造数据库链接池，链接池配置类似HikariCP（https://github.com/brettwooldridge/HikariCP）

   let settings = Config::builder()
        .add_source(config::File::with_name("conf/application.yml"))
        .build()
        .unwrap();

    let db_num = settings.get_int("db.num").unwrap();
    let mut conns: Vec<DatabaseConnection> = Vec::new();

    let max_connections = settings
        .get_int("db.pool.config.maximumPoolSize")
        .unwrap_or(100) as u32;
    let min_connections = settings
        .get_int("db.pool.config.minimumPoolSize")
        .unwrap_or(1) as u32;
    let connect_timeout = settings
        .get_int("db.pool.config.connectionTimeout")
        .unwrap_or(30) as u64;
    let acquire_timeout = settings
        .get_int("db.pool.config.initializationFailTimeout")
        .unwrap_or(1) as u64;
    let idle_timeout = settings.get_int("db.pool.config.idleTimeout").unwrap_or(10) as u64;
    let max_lifetime = settings.get_int("db.pool.config.maxLifetime").unwrap_or(30) as u64;

    for i in 0..db_num {
        let url = &settings
            .get_string(format!("db.url.{}", i).as_str())
            .unwrap();

        let mut opt = ConnectOptions::new(url);

        opt.max_connections(max_connections)
            .min_connections(min_connections)
            .connect_timeout(Duration::from_secs(connect_timeout))
            .acquire_timeout(Duration::from_secs(acquire_timeout))
            .idle_timeout(Duration::from_secs(idle_timeout))
            .max_lifetime(Duration::from_secs(max_lifetime))
            .sqlx_logging(true)
            .sqlx_logging_level(log::LevelFilter::Info);

        let db = Database::connect(opt).await.unwrap();

        conns.push(db);
    }

条件查询，示例为查询所有namespace

        let tenant_infos: Vec<tenant_info::Model> = tenant_info::Entity::find()
            .filter(tenant_info::Column::Kp.eq(NamespaceOperationService::DEFAULT_KP))
            .all(db)
            .await
            .unwrap();

in查询，示例为根据namespace ID集合，查询配置数量

#[derive(Debug, FromQueryResult)]
        struct SelectResult {
            tenant_id: Option<String>,
            count: i32,
        }

        let mut config_infos = config_info::Entity::find()
            .select_only()
            .column(config_info::Column::TenantId)
            .column_as(config_info::Column::Id.count(), "count")
            .filter(config_info::Column::TenantId.is_in(tenant_ids))
            .filter(config_info::Column::TenantId.is_not_null())
            .group_by(config_info::Column::TenantId)
            .into_model::<SelectResult>()
            .all(db)
            .await
            .unwrap()
            .iter()
            .map(|x| (x.tenant_id.clone().unwrap_or_default(), x.count))
            .collect::<HashMap<String, i32>>();