Support for INTERVAL inside window frames (#655)

* Add support to for INTERVAL inside window queries

* Remove the unnecessary ancillary struct Interval

* Convert Window Frame Bound to Expr

* remove unnecessary changes

* remove unnecessary changes

Co-authored-by: Mehmet Ozan Kabak <ozankabak@gmail.com>

Author: mustafasrepo

src/ast/mod.rs

@@ -906,9 +906,9 @@ pub enum WindowFrameBound {
     /// `CURRENT ROW`
     CurrentRow,
     /// `<N> PRECEDING` or `UNBOUNDED PRECEDING`
-    Preceding(Option<u64>),
+    Preceding(Option<Box<Expr>>),
     /// `<N> FOLLOWING` or `UNBOUNDED FOLLOWING`.
-    Following(Option<u64>),
+    Following(Option<Box<Expr>>),
 }
 
 impl fmt::Display for WindowFrameBound {

src/parser.rs

@@ -623,7 +623,6 @@ impl<'a> Parser<'a> {
         } else {
             None
         };
-
         Ok(Expr::Function(Function {
             name,
             args,
@@ -685,7 +684,10 @@ impl<'a> Parser<'a> {
             let rows = if self.parse_keyword(Keyword::UNBOUNDED) {
                 None
             } else {
-                Some(self.parse_literal_uint()?)
+                Some(Box::new(match self.peek_token() {
+                    Token::SingleQuotedString(_) => self.parse_interval()?,
+                    _ => self.parse_expr()?,
+                }))
             };
             if self.parse_keyword(Keyword::PRECEDING) {
                 Ok(WindowFrameBound::Preceding(rows))

tests/sqlparser_common.rs

@@ -2940,13 +2940,17 @@ fn parse_window_functions() {
                ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW), \
                avg(bar) OVER (ORDER BY a \
                RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING), \
+               sum(bar) OVER (ORDER BY a \
+               RANGE BETWEEN INTERVAL '1' DAY PRECEDING AND INTERVAL '1 MONTH' FOLLOWING), \
+               COUNT(*) OVER (ORDER BY a \
+               RANGE BETWEEN INTERVAL '1 DAY' PRECEDING AND INTERVAL '1 DAY' FOLLOWING), \
                max(baz) OVER (ORDER BY a \
                ROWS UNBOUNDED PRECEDING), \
                sum(qux) OVER (ORDER BY a \
                GROUPS BETWEEN 1 PRECEDING AND 1 FOLLOWING) \
                FROM foo";
     let select = verified_only_select(sql);
-    assert_eq!(5, select.projection.len());
+    assert_eq!(7, select.projection.len());
     assert_eq!(
         &Expr::Function(Function {
             name: ObjectName(vec![Ident::new("row_number")]),