toasty_core/stmt/
func_count.rs

1use super::{Expr, ExprFunc};
2
3/// The SQL `COUNT` aggregate function.
4///
5/// When `arg` is `None`, represents `COUNT(*)` (counts all rows). When `arg` is
6/// `Some`, counts the number of rows where the argument expression is non-null.
7///
8/// # Examples
9///
10/// ```text
11/// COUNT(*)                       // arg: None, filter: None
12/// COUNT(column)                  // arg: Some(column), filter: None
13/// COUNT(*) FILTER (WHERE cond)   // arg: None, filter: Some(cond)
14/// ```
15#[derive(Clone, Debug, PartialEq)]
16pub struct FuncCount {
17    /// The expression to count. `None` means `COUNT(*)`.
18    pub arg: Option<Box<Expr>>,
19
20    /// Optional filter applied before counting.
21    pub filter: Option<Box<Expr>>,
22}
23
24impl Expr {
25    /// Creates a `COUNT(*)` expression.
26    pub fn count_star() -> Self {
27        Self::Func(ExprFunc::Count(FuncCount {
28            arg: None,
29            filter: None,
30        }))
31    }
32}
33
34impl From<FuncCount> for ExprFunc {
35    fn from(value: FuncCount) -> Self {
36        Self::Count(value)
37    }
38}
39
40impl From<FuncCount> for Expr {
41    fn from(value: FuncCount) -> Self {
42        Self::Func(value.into())
43    }
44}
toasty_core/stmt/func_count.rs

toasty_core/stmt/
func_count.rs
