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use self::private::SqlOrdAggregate;
#[cfg(doc)]
use super::aggregate_expressions::{AggregateExpressionMethods, WindowExpressionMethods};
use crate::expression::functions::declare_sql_function;
#[declare_sql_function]
extern "SQL" {
/// Represents a SQL `MAX` function. This function can only take types which are
/// ordered.
///
/// ## Window Function Usage
///
/// This function can be used as window function. See [`WindowExpressionMethods`] for details
///
/// ## Aggregate Function Expression
///
/// This function can be used as aggregate expression. See [`AggregateExpressionMethods`] for details.
///
/// # Examples
///
/// ## Normal function usage
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// #
/// # fn main() {
/// # use schema::animals::dsl::*;
/// # let connection = &mut establish_connection();
/// assert_eq!(Ok(Some(8)), animals.select(max(legs)).first(connection));
/// # }
/// ```
///
/// ## Window function
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// #
/// # fn main() {
/// # use schema::animals::dsl::*;
/// # let connection = &mut establish_connection();
/// let res = animals
/// .select((name, max(legs).partition_by(id)))
/// .load::<(Option<String>, Option<i32>)>(connection);
///
/// assert_eq!(
/// Ok(vec![(Some("Jack".into()), Some(4)), (None, Some(8))]),
/// res
/// );
/// # }
/// ```
///
///
/// ## Aggregate function expression
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// #
/// # fn main() {
/// # use schema::animals::dsl::*;
/// # let connection = &mut establish_connection();
/// # #[cfg(not(feature = "mysql"))]
/// assert_eq!(
/// Ok(Some(4)),
/// animals
/// .select(max(legs).aggregate_filter(legs.lt(8)))
/// .first(connection)
/// );
/// # }
/// ```
#[aggregate]
#[window]
fn max<ST: SqlOrdAggregate>(expr: ST) -> ST::Ret;
/// Represents a SQL `MIN` function. This function can only take types which are
/// ordered.
///
/// ## Window Function Usage
///
/// This function can be used as window function. See [`WindowExpressionMethods`] for details
///
/// ## Aggregate Function Expression
///
/// This function can be used as aggregate expression. See [`AggregateExpressionMethods`] for details.
///
/// # Examples
///
/// ## Normal function usage
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// #
/// # fn main() {
/// # use schema::animals::dsl::*;
/// # let connection = &mut establish_connection();
/// assert_eq!(Ok(Some(4)), animals.select(min(legs)).first(connection));
/// # }
/// ```
///
/// ## Window function
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// #
/// # fn main() {
/// # use schema::animals::dsl::*;
/// # let connection = &mut establish_connection();
/// let res = animals
/// .select((name, min(legs).partition_by(id)))
/// .load::<(Option<String>, Option<i32>)>(connection);
///
/// assert_eq!(
/// Ok(vec![(Some("Jack".into()), Some(4)), (None, Some(8))]),
/// res
/// );
/// # }
/// ```
///
/// ## Aggregate function expression
///
/// ```rust
/// # include!("../../doctest_setup.rs");
/// # use diesel::dsl::*;
/// #
/// # fn main() {
/// # use schema::animals::dsl::*;
/// # let connection = &mut establish_connection();
/// # #[cfg(not(feature = "mysql"))]
/// assert_eq!(
/// Ok(Some(8)),
/// animals
/// .select(min(legs).aggregate_filter(legs.gt(4)))
/// .first(connection)
/// );
/// # }
/// ```
#[aggregate]
#[window]
fn min<ST: SqlOrdAggregate>(expr: ST) -> ST::Ret;
}
mod private {
use crate::sql_types::{IntoNullable, SingleValue, SqlOrd, SqlType};
pub trait SqlOrdAggregate: SingleValue {
type Ret: SqlType + SingleValue;
}
impl<T> SqlOrdAggregate for T
where
T: SqlOrd + IntoNullable + SingleValue,
T::Nullable: SqlType + SingleValue,
{
type Ret = T::Nullable;
}
}