Support GoogleSQL inline aggregate WHERE filter: AGG(expr WHERE cond)

src/ast/mod.rs

@@ -8265,6 +8265,12 @@ pub enum FunctionArgumentClause {
     ///
     /// [BigQuery]: https://cloud.google.com/bigquery/docs/reference/standard-sql/navigation_functions#first_value
     IgnoreOrRespectNulls(NullTreatment),
+    /// The inline `WHERE` filter clause on a GoogleSQL aggregate, e.g.
+    /// `COUNT(* WHERE cond)` / `SUM(x WHERE cond)` / `ARRAY_AGG(x WHERE cond ORDER BY ..)`.
+    /// Equivalent to the standard `AGG(x) FILTER (WHERE cond)`.
+    ///
+    /// [BigQuery]: https://cloud.google.com/bigquery/docs/reference/standard-sql/aggregate_functions#grouping_and_filtering
+    Where(Expr),
     /// Specifies the the ordering for some ordered set aggregates, e.g. `ARRAY_AGG` on [BigQuery].
     ///
     /// [BigQuery]: https://cloud.google.com/bigquery/docs/reference/standard-sql/aggregate_functions#array_agg
@@ -8306,6 +8312,7 @@ impl fmt::Display for FunctionArgumentClause {
             FunctionArgumentClause::IgnoreOrRespectNulls(null_treatment) => {
                 write!(f, "{null_treatment}")
             }
+            FunctionArgumentClause::Where(expr) => write!(f, "WHERE {expr}"),
             FunctionArgumentClause::OrderBy(order_by) => {
                 write!(f, "ORDER BY {}", display_comma_separated(order_by))
             }

src/ast/spans.rs

@@ -1794,6 +1794,7 @@ impl Spanned for FunctionArgumentClause {
     fn span(&self) -> Span {
         match self {
             FunctionArgumentClause::IgnoreOrRespectNulls(_) => Span::empty(),
+            FunctionArgumentClause::Where(expr) => expr.span(),
             FunctionArgumentClause::OrderBy(vec) => union_spans(vec.iter().map(|i| i.expr.span())),
             FunctionArgumentClause::Limit(expr) => expr.span(),
             FunctionArgumentClause::OnOverflow(_) => Span::empty(),

src/parser/mod.rs

@@ -18502,6 +18502,14 @@ impl<'a> Parser<'a> {
         let duplicate_treatment = self.parse_duplicate_treatment()?;
         let args = self.parse_comma_separated(Parser::parse_function_args)?;
 
+        // GoogleSQL inline aggregate filter: `AGG(expr WHERE cond [ORDER BY ..])`.
+        // Precedes ORDER BY / LIMIT / HAVING; equivalent to `AGG(expr) FILTER (WHERE cond)`.
+        if dialect_of!(self is GenericDialect | BigQueryDialect)
+            && self.parse_keyword(Keyword::WHERE)
+        {
+            clauses.push(FunctionArgumentClause::Where(self.parse_expr()?));
+        }
+
         if self.dialect.supports_window_function_null_treatment_arg() {
             if let Some(null_treatment) = self.parse_null_treatment()? {
                 clauses.push(FunctionArgumentClause::IgnoreOrRespectNulls(null_treatment));

tests/sqlparser_bigquery.rs

@@ -2950,3 +2950,28 @@ fn test_create_snapshot_table() {
         "CREATE SNAPSHOT TABLE IF NOT EXISTS dataset_id.table1 CLONE dataset_id.table2 FOR SYSTEM_TIME AS OF TIMESTAMP_SUB(CURRENT_TIMESTAMP(), INTERVAL 1 HOUR) OPTIONS(expiration_timestamp = TIMESTAMP '2025-01-01 00:00:00 UTC')",
     );
 }
+
+#[test]
+fn parse_aggregate_with_where_filter() {
+    // GoogleSQL allows an inline `WHERE` filter inside an aggregate call,
+    // e.g. `COUNT(* WHERE cond)` / `SUM(x WHERE cond)`. It is the in-argument
+    // spelling of the standard `AGG(x) FILTER (WHERE cond)`. Round-trips via
+    // the `FunctionArgumentClause::Where` clause.
+    bigquery().verified_stmt("SELECT COUNT(* WHERE x > 1) FROM t");
+    bigquery().verified_stmt("SELECT SUM(x WHERE y > 0) FROM t");
+    // Co-occurs with (and precedes) an in-argument ORDER BY.
+    bigquery().verified_stmt("SELECT ARRAY_AGG(x WHERE x > 100 ORDER BY x DESC) FROM t");
+
+    // The filter is captured as a FunctionArgumentClause::Where.
+    let select = bigquery().verified_only_select("SELECT SUM(salary WHERE dept = 1) FROM emp");
+    let SelectItem::UnnamedExpr(Expr::Function(func)) = &select.projection[0] else {
+        panic!("expected a function projection");
+    };
+    let FunctionArguments::List(list) = &func.args else {
+        panic!("expected a function argument list");
+    };
+    assert!(list
+        .clauses
+        .iter()
+        .any(|c| matches!(c, FunctionArgumentClause::Where(_))));
+}