rust连接postgresql数据库

同步操作

引入crate：

复制代码

postgres = "0.19.7"

rust 复制代码

use postgres::{Client, NoTls, error::Error};

fn main() -> Result<(), Error> {
    let mut client = Client::connect("host=localhost port=5432 dbname=xxxxxdb user=postgres password=123456", NoTls).unwrap();
    for row in client.query("select id,name,file_name,create_time::TEXT,valid from xxxxx", &[])?{
        let id: i32 = row.get("id");
        let name: &str = row.get("name");
        let file_name: &str = row.get("file_name");
        let create_time: &str = row.get(3);
        let valid: bool = row.get(4);
        println!("id:{}, name:{}, file_name:{},create_time:{:?} valid:{}", id, name, file_name,create_time, valid);
    }

     let rows = client.query("select count(*)::integer as a from xxxxx where id=$1", &[&1])?;
     let cnt: i32 = rows[0].get("a");
     println!("cnt={}", cnt);

    Ok(())
}

注意：用户名不要使用root。否则报错：

thread 'main' panicked at src\main.rs:5:115:

called `Result::unwrap()` on an `Err` value: Error { kind: Parse, cause: Some(Custom { kind: InvalidInput, error: Utf8Error { valid_up_to: 0, error_len: Some(1) } }) }

注意：select count(*) ::integer as a from xxxx的写法，做postgres内的类型转换，否则count(*)默认作为i8返回，rust获取数据时报错。

异步操作

引入Crate：

复制代码

tokio = {version = "1.35.1", features = ["full"]}
tokio-postgres = "0.7.10"
chrono = "0.4.34"

rust 复制代码

use tokio_postgres::{NoTls, Error};
use chrono::prelude::{DateTime, Utc};
use std::time::SystemTime;

#[tokio::main]
async fn main() -> Result<(), Error> {
    println!("测试tokio异步版本postgres操作");
    let (client, connection) = tokio_postgres::connect("host=localhost port=5432 dbname=xxxxxdb user=postgres password=123456", NoTls).await.unwrap();
    //启动线程监控数据库连接是否正常
    tokio::spawn(async move {
        if let Err(e) = connection.await{
            eprintln!("connection error:{}", e);
        }
    });
    let rows = client.query("select id,name,file_name,create_time,valid from xxxxx", &[]).await?;
    for row in rows{
        let id: i32 = row.get("id");
        let name: &str = row.get("name");
        let file_name: String = row.get("file_name");
        let create_time: SystemTime = row.get("create_time");
        let dt: DateTime<Utc> = create_time.clone().into();
        println!("id={}, name={}, file_name={}, create_time={}", id, name, file_name, dt.format("%Y-%M-%d %H:%m:%S"));
    }

    let rows = client.query("select max(id)::integer from xxxxx", &[]).await?;
    let max_id:i32 = rows[0].get(0);
    println!("max id={}", max_id);
    let new_id = max_id + 1;
    let new_name: String = format!("xxxxx-{}", new_id);
    let new_file_name: String = format!("xxxxx_file_name-{}", new_id);
    let modify_row_cnt = client.execute("insert into xxxxx(id,name,file_name,create_time,valid) values($1,$2,$3,$4,$5)", &[&new_id, &new_name, &new_file_name, &SystemTime::now(), &true]).await?;
    println!("affect row count:{}", modify_row_cnt);

    let affect_row_count = client.execute("update xxxxx set file_name='xxxxx_file_name-' || id::TEXT where file_name=''", &[]).await?;
    println!("affect row count:{}", affect_row_count);

    let affect_row_count = client.execute("delete from xxxxx where id=$1", &[&new_id]).await?;
    println!("delete row count:{}", affect_row_count);

    let trans = client.transaction().await?;
    trans.execute("update xxxxx set valid=$1,remark=name || id::TEXT where id=$2", &[&false, &1]).await?;
    trans.execute("update xxxxx set valid=$1,remark=name || id::TEXT where id=$2", &[&true, &2]).await?;
    trans.commit().await?;
    Ok(())
}

注意：postgresql中的timestamp类型可以直接转换为rust中的SystemTime；要转换为我们熟悉的年月日时分秒格式，还需要借助chrono crate。

代码中含增、删、改、查、事务范例。