homework-jianmu/docs/examples/rust/nativeexample/examples/query.rs

102 lines
3.0 KiB
Rust

use taos::*;
use chrono::Local;
use chrono::DateTime;
#[tokio::main]
async fn main() -> anyhow::Result<()> {
let dsn = "taos://localhost:6030";
let builder = TaosBuilder::from_dsn(dsn)?;
let taos = builder.build().await?;
// ANCHOR: create_db_and_table
let db = "power";
// create database
taos.exec_many([
format!("CREATE DATABASE IF NOT EXISTS `{db}`"),
format!("USE `{db}`"),
])
.await?;
println!("Create database power successfully.");
// create super table
taos.exec_many([
"CREATE STABLE IF NOT EXISTS `meters` (`ts` TIMESTAMP, `current` FLOAT, `voltage` INT, `phase` FLOAT) \
TAGS (`groupid` INT, `location` BINARY(24))",
]).await?;
println!("Create stable meters successfully.");
// ANCHOR_END: create_db_and_table
// ANCHOR: insert_data
let inserted = taos.exec(r#"INSERT INTO
power.d1001 USING power.meters TAGS(2,'California.SanFrancisco')
VALUES
(NOW + 1a, 10.30000, 219, 0.31000)
(NOW + 2a, 12.60000, 218, 0.33000)
(NOW + 3a, 12.30000, 221, 0.31000)
power.d1002 USING power.meters TAGS(3, 'California.SanFrancisco')
VALUES
(NOW + 1a, 10.30000, 218, 0.25000) "#).await?;
println!("inserted: {} rows to power.meters successfully.", inserted);
// ANCHOR_END: insert_data
// ANCHOR: query_data
// query data, make sure the database and table are created before
let mut result = taos.query("SELECT ts, current, location FROM power.meters limit 100").await?;
for field in result.fields() {
println!("got field: {}", field.name());
}
let mut rows = result.rows();
let mut nrows = 0;
while let Some(row) = rows.try_next().await? {
for (col, (name, value)) in row.enumerate() {
println!(
"[{}] got value in col {} (named `{:>8}`): {}",
nrows, col, name, value
);
}
nrows += 1;
}
// ANCHOR_END: query_data
// ANCHOR: query_data_2
// query data, make sure the database and table are created before
#[derive(Debug, serde::Deserialize)]
#[allow(dead_code)]
struct Record {
// deserialize timestamp to chrono::DateTime<Local>
ts: DateTime<Local>,
// float to f32
current: Option<f32>,
// int to i32
voltage: Option<i32>,
phase: Option<f32>,
groupid: i32,
// binary/varchar to String
location: String,
}
let records: Vec<Record> = taos
.query("select ts, current, voltage, phase, groupid, location from power.meters limit 100")
.await?
.deserialize()
.try_collect()
.await?;
dbg!(records);
// ANCHOR_END: query_data_2
// ANCHOR: query_with_req_id
let result = taos.query_with_req_id("SELECT ts, current, location FROM power.meters limit 1", 1).await?;
for field in result.fields() {
println!("got field: {}", field.name());
}
println!("query with reqId successfully");
// ANCHOR_END: query_with_req_id
Ok(())
}