diesel/expression/functions/
aggregate_folding.rs

1use sql_types::Foldable;
2
3sql_function! {
4    /// Represents a SQL `SUM` function. This function can only take types which are
5    /// Foldable.
6    ///
7    /// # Examples
8    ///
9    /// ```rust
10    /// # #[macro_use] extern crate diesel;
11    /// # include!("../../doctest_setup.rs");
12    /// # use diesel::dsl::*;
13    /// #
14    /// # fn main() {
15    /// #     use schema::animals::dsl::*;
16    /// #     let connection = establish_connection();
17    /// assert_eq!(Ok(Some(12i64)), animals.select(sum(legs)).first(&connection));
18    /// # }
19    /// ```
20    #[aggregate]
21    fn sum<ST: Foldable>(expr: ST) -> ST::Sum;
22}
23
24sql_function! {
25    /// Represents a SQL `AVG` function. This function can only take types which are
26    /// Foldable.
27    ///
28    /// # Examples
29    ///
30    /// ```rust
31    /// # #[macro_use] extern crate diesel;
32    /// # include!("../../doctest_setup.rs");
33    /// # use diesel::dsl::*;
34    /// # #[cfg(feature = "bigdecimal")]
35    /// # extern crate bigdecimal;
36    /// #
37    /// # fn main() {
38    /// #     run_test().unwrap();
39    /// # }
40    /// #
41    /// # table! {
42    /// #     numbers (number) {
43    /// #         number -> Integer,
44    /// #     }
45    /// # }
46    /// #
47    /// # #[cfg(all(feature = "numeric", any(feature = "postgres", not(feature = "sqlite"))))]
48    /// # fn run_test() -> QueryResult<()> {
49    /// #     use bigdecimal::BigDecimal;
50    /// #     use numbers::dsl::*;
51    /// #     let conn = establish_connection();
52    /// #     conn.execute("DROP TABLE IF EXISTS numbers")?;
53    /// #     conn.execute("CREATE TABLE numbers (number INTEGER)")?;
54    /// diesel::insert_into(numbers)
55    ///     .values(&vec![number.eq(1), number.eq(2)])
56    ///     .execute(&conn)?;
57    /// let average = numbers.select(avg(number)).get_result(&conn)?;
58    /// let expected = "1.5".parse::<BigDecimal>().unwrap();
59    /// assert_eq!(Some(expected), average);
60    /// #     Ok(())
61    /// # }
62    /// #
63    /// # #[cfg(not(all(feature = "numeric", any(feature = "postgres", not(feature = "sqlite")))))]
64    /// # fn run_test() -> QueryResult<()> {
65    /// #     Ok(())
66    /// # }
67    #[aggregate]
68    fn avg<ST: Foldable>(expr: ST) -> ST::Avg;
69}
diesel/expression/functions/aggregate_folding.rs

diesel/expression/functions/
aggregate_folding.rs
