Support HAVING without GROUP BY

...which is weird but allowed:
https://jakewheat.github.io/sql-overview/sql-2011-foundation-grammar.html#table-expression
https://dba.stackexchange.com/a/57453/15599

Also add a test for GROUP BY .. HAVING

Author: nickolay

src/dialect/keywords.rs

@@ -420,7 +420,7 @@ define_keywords!(
 /// can be parsed unambiguously without looking ahead.
 pub const RESERVED_FOR_TABLE_ALIAS: &[&str] = &[
     // Reserved as both a table and a column alias:
-    WITH, SELECT, WHERE, GROUP, ORDER, LIMIT, OFFSET, FETCH, UNION, EXCEPT, INTERSECT,
+    WITH, SELECT, WHERE, GROUP, HAVING, ORDER, LIMIT, OFFSET, FETCH, UNION, EXCEPT, INTERSECT,
     // Reserved only as a table alias in the `FROM`/`JOIN` clauses:
     ON, JOIN, INNER, CROSS, FULL, LEFT, RIGHT, NATURAL, USING,
 ];
@@ -429,7 +429,7 @@ pub const RESERVED_FOR_TABLE_ALIAS: &[&str] = &[
 /// can be parsed unambiguously without looking ahead.
 pub const RESERVED_FOR_COLUMN_ALIAS: &[&str] = &[
     // Reserved as both a table and a column alias:
-    WITH, SELECT, WHERE, GROUP, ORDER, LIMIT, OFFSET, FETCH, UNION, EXCEPT, INTERSECT,
+    WITH, SELECT, WHERE, GROUP, HAVING, ORDER, LIMIT, OFFSET, FETCH, UNION, EXCEPT, INTERSECT,
     // Reserved only as a column alias in the `SELECT` clause:
     FROM,
 ];

src/sqlparser.rs

@@ -1566,6 +1566,11 @@ impl Parser {
         }
         let projection = self.parse_select_list()?;
 
+        // Note that for keywords to be properly handled here, they need to be
+        // added to `RESERVED_FOR_COLUMN_ALIAS` / `RESERVED_FOR_TABLE_ALIAS`,
+        // otherwise they may be parsed as an alias as part of the `projection`
+        // or `from`.
+
         let mut from = vec![];
         if self.parse_keyword("FROM") {
             loop {

tests/sqlparser_common.rs

@@ -789,6 +789,29 @@ fn parse_select_group_by() {
     );
 }
 
+#[test]
+fn parse_select_having() {
+    let sql = "SELECT foo FROM bar GROUP BY foo HAVING COUNT(*) > 1";
+    let select = verified_only_select(sql);
+    assert_eq!(
+        Some(ASTNode::SQLBinaryOp {
+            left: Box::new(ASTNode::SQLFunction(SQLFunction {
+                name: SQLObjectName(vec!["COUNT".to_string()]),
+                args: vec![ASTNode::SQLWildcard],
+                over: None,
+                distinct: false
+            })),
+            op: SQLBinaryOperator::Gt,
+            right: Box::new(ASTNode::SQLValue(Value::Long(1)))
+        }),
+        select.having
+    );
+
+    let sql = "SELECT 'foo' HAVING 1 = 1";
+    let select = verified_only_select(sql);
+    assert!(select.having.is_some());
+}
+
 #[test]
 fn parse_limit_accepts_all() {
     one_statement_parses_to(