From 76ecc179578a04763e2472d173bf0ce88edb3ea8 Mon Sep 17 00:00:00 2001
From: Vedat Can Keklik <vcankeklik@gmail.com>
Date: Sat, 9 Dec 2023 17:11:52 +0300
Subject: [PATCH] feat: GROUP BY + HAVING clauses

---
 server/src/lang/ast/sql.rs |  2 +-
 server/src/lang/parser.rs  | 38 +++++++++++++++++++++++++++++++++-----
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/server/src/lang/ast/sql.rs b/server/src/lang/ast/sql.rs
index cbed1c8f..d4136a0f 100644
--- a/server/src/lang/ast/sql.rs
+++ b/server/src/lang/ast/sql.rs
@@ -82,7 +82,7 @@ pub struct SelectCore {
     pub projection: Vec<SqlProjection>,
     pub from: Option<SqlFrom>,
     pub r#where: Option<SqlExpr>,
-    pub group_by: Option<SqlExpr>,
+    pub group_by: Option<Vec<SqlExpr>>,
     pub having: Option<SqlExpr>,
 }
 
diff --git a/server/src/lang/parser.rs b/server/src/lang/parser.rs
index 4c5c1ebb..457409e3 100644
--- a/server/src/lang/parser.rs
+++ b/server/src/lang/parser.rs
@@ -520,16 +520,44 @@ impl<'a> Parser<'a> {
             SqlDistinct::All
         }*/
 
+        let projection = self.sql_projection();
+        let from = self.sql_from()?;
+        let r#where = self.sql_where()?;
+        let group_by = self.sql_group_by()?;
+        let having = if group_by.is_some() && self.match_next(skw!(Having)) {
+            Some(SqlExpr::Default(self.expression()?))
+        } else {
+            None
+        };
+
         Ok(SelectCore {
             distinct,
-            projection: self.sql_projection(),
-            from: self.sql_from()?,
-            r#where: self.sql_where()?,
-            group_by: None, // TODO(vck)
-            having: None,   // TODO(vck)
+            projection,
+            from,
+            r#where,
+            group_by,
+            having,
         })
     }
 
+    fn sql_group_by(&mut self) -> ParseResult<Option<Vec<SqlExpr>>> {
+        if self.match_next(skw!(Group)) {
+            self.expected(skw!(By))?;
+            let mut groups: Vec<SqlExpr> = vec![];
+
+            loop {
+                let group_expr = self.expression()?;
+                groups.push(SqlExpr::Default(group_expr));
+                if !self.match_next(sym!(Comma)) {
+                    break;
+                }
+            }
+            Ok(Some(groups))
+        } else {
+            Ok(None)
+        }
+    }
+
     fn sql_projection(&mut self) -> Vec<SqlProjection> {
         let mut projections: Vec<SqlProjection> = vec![];
         loop {