使用 Rust 的 u32 让 PostgreSQL 实现 MySQL 的 INT UNSIGNED

i32 和 u32 的转换

无论 Rust 的 i32 还是 PostgreSQL 的 INT，当它们的值达到取值范围的最大值时，它们会溢出为最小值。

请看代码：

#[test]
fn test_max_i32_plus_1() {
    let max_i32 = i32::max_value();
    let min_i32 = i32::min_value();

    let from_max_i32 = (max_i32 as u32) + 1;
    let from_min_i32 = min_i32 as u32;
    assert!(from_max_i32 == from_min_i32);
}

使用 Rust 的 u32 让 PostgreSQL 实现 MySQL 的 INT UNSIGNED

SQL 语句

CREATE TABLE test_int_to_u32(
	hit INT NOT NULL
);

CREATE TABLE test_serial_to_u32(
	id SERIAL PRIMARY KEY
);

依赖

[dependencies]
tokio={version="1", features=["full"]}
sqlx = { version = "0.6", features = [ "runtime-tokio-native-tls" , "postgres" ] }

代码演示

fn main() {
    println!("Hello, world!");
}

pub struct PgIntAndRustU32 {
    pub hit: u32,
}

pub struct PgSerialAndRustU32 {
    pub id: u32,
}

#[cfg(test)]
mod test {
    use super::*;
    use sqlx::{postgres::PgPoolOptions, Row};

    #[test]
    fn test_max_i32_plus_1() {
        let max_i32 = i32::max_value();
        let min_i32 = i32::min_value();

        let from_max_i32 = (max_i32 as u32) + 1;
        let from_min_i32 = min_i32 as u32;
        assert!(from_max_i32 == from_min_i32);
    }

    #[tokio::test]
    async fn test_pg_int_and_rust_u32() {
        let pool = PgPoolOptions::new().max_connections(3).connect("postgres://axum_rs:[email protected]/axum_rs").await.unwrap();
        let max_i32 = i32::max_value();
        let i: u32 = (max_i32 as u32) + 1;
        sqlx::query("INSERT INTO test_int_to_u32(hit) VALUES ($1)")
            .bind(i as i32)
            .execute(&pool)
            .await
            .unwrap();
    }
    #[tokio::test]
    async fn test_pg_int_and_rust_u32_read() {
        let pool = PgPoolOptions::new().max_connections(3).connect("postgres://axum_rs:[email protected]/axum_rs").await.unwrap();
        let row = sqlx::query("SELECT hit FROM test_int_to_u32")
            .fetch_one(&pool)
            .await
            .unwrap();
        let hit: i32 = row.get(0);
        let obj = PgIntAndRustU32 { hit: hit as u32 };
        assert!(obj.hit == (i32::max_value() as u32) + 1);
        assert!(obj.hit as i32 == i32::min_value());
    }

    #[tokio::test]
    async fn test_pg_serial_and_rust_u32() {
        let pool = PgPoolOptions::new().max_connections(3).connect("postgres://axum_rs:[email protected]/axum_rs").await.unwrap();
        let max_i32 = i32::max_value();
        let i: u32 = (max_i32 as u32) + 1;
        sqlx::query("INSERT INTO test_serial_to_u32(id) VALUES ($1)")
            .bind(i as i32)
            .execute(&pool)
            .await
            .unwrap();
    }
    #[tokio::test]
    async fn test_pg_serial_and_rust_u32read() {
        let pool = PgPoolOptions::new().max_connections(3).connect("postgres://axum_rs:[email protected]/axum_rs").await.unwrap();
        let row = sqlx::query("SELECT hit FROM test_serial_to_u32")
            .fetch_one(&pool)
            .await
            .unwrap();
        let id: i32 = row.get(0);
        let obj = PgSerialAndRustU32 { id: id as u32 };
        assert!(obj.id == (i32::max_value() as u32) + 1);
        assert!(obj.id as i32 == i32::min_value());
    }
}