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use crate::expression::functions::sql_function;
use crate::sql_types::Foldable;
sql_function! {
/// Represents a SQL `SUM` function. This function can only take types which are
/// Foldable.
///
/// # Examples
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// #
/// # fn main() {
/// # use schema::animals::dsl::*;
/// # let connection = &mut establish_connection();
/// assert_eq!(Ok(Some(12i64)), animals.select(sum(legs)).first(connection));
/// # }
/// ```
#[aggregate]
fn sum<ST: Foldable>(expr: ST) -> ST::Sum;
}
sql_function! {
/// Represents a SQL `AVG` function. This function can only take types which are
/// Foldable.
///
/// # Examples
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// # #[cfg(feature = "bigdecimal")]
/// # extern crate bigdecimal;
/// #
/// # fn main() {
/// # run_test().unwrap();
/// # }
/// #
/// # table! {
/// # numbers (number) {
/// # number -> Integer,
/// # }
/// # }
/// #
/// # #[cfg(all(feature = "numeric", any(feature = "postgres", not(feature = "sqlite"))))]
/// # fn run_test() -> QueryResult<()> {
/// # use bigdecimal::BigDecimal;
/// # use self::numbers::dsl::*;
/// # let conn = &mut establish_connection();
/// # diesel::sql_query("DROP TABLE IF EXISTS numbers").execute(conn)?;
/// # diesel::sql_query("CREATE TABLE numbers (number INTEGER)").execute(conn)?;
/// diesel::insert_into(numbers)
/// .values(&vec![number.eq(1), number.eq(2)])
/// .execute(conn)?;
/// let average = numbers.select(avg(number)).get_result(conn)?;
/// let expected = "1.5".parse::<BigDecimal>().unwrap();
/// assert_eq!(Some(expected), average);
/// # Ok(())
/// # }
/// #
/// # #[cfg(not(all(feature = "numeric", any(feature = "postgres", not(feature = "sqlite")))))]
/// # fn run_test() -> QueryResult<()> {
/// # Ok(())
/// # }
#[aggregate]
fn avg<ST: Foldable>(expr: ST) -> ST::Avg;
}