Function diesel::expression::dsl::count_star [] [src]

pub fn count_star() -> CountStar

Creates a SQL COUNT(*) expression

For selecting the count of a query, and nothing else, you can just call count on the query instead.

As with most bare functions, this is not exported by default. You can import it specifically as diesel::expression::count_star, or glob import diesel::expression::dsl::*

Example

#[macro_use] extern crate diesel;

include!("src/doctest_setup.rs");

use diesel::expression::dsl::*;

table! {

users {

id -> Serial,

name -> VarChar,

}

}

fn main() {

use self::users::dsl::*;

let connection = establish_connection();

assert_eq!(Ok(Some(2)), users.select(count_star()).first(&connection));

}