Fix: workaround bigquery grouped alias with order

sqlglot/dialects/bigquery.py

@@ -107,6 +107,34 @@ def _unqualify_unnest(expression: exp.Expression) -> exp.Expression:
     return expression
 
 
+# https://issuetracker.google.com/issues/162294746
+# workaround for bigquery bug when grouping by an expression and then ordering
+# WITH x AS (SELECT 1 y)
+# SELECT y + 1 z
+# FROM x
+# GROUP BY x + 1
+# ORDER by z
+def _alias_ordered_group(expression: exp.Expression) -> exp.Expression:
+    if isinstance(expression, exp.Select):
+        group = expression.args.get("group")
+        order = expression.args.get("order")
+
+        if group and order:
+            aliases = {
+                select.this: select.args["alias"]
+                for select in expression.selects
+                if isinstance(select, exp.Alias)
+            }
+
+            for e in group.expressions:
+                alias = aliases.get(e)
+
+                if alias:
+                    e.replace(exp.column(alias))
+
+    return expression
+
+
 def _pushdown_cte_column_names(expression: exp.Expression) -> exp.Expression:
     """BigQuery doesn't allow column names when defining a CTE, so we try to push them down."""
     if isinstance(expression, exp.CTE) and expression.alias_column_names:
@@ -360,7 +388,12 @@ class Generator(generator.Generator):
             ),
             exp.RegexpLike: rename_func("REGEXP_CONTAINS"),
             exp.Select: transforms.preprocess(
-                [transforms.explode_to_unnest, _unqualify_unnest, transforms.eliminate_distinct_on]
+                [
+                    transforms.explode_to_unnest,
+                    _unqualify_unnest,
+                    transforms.eliminate_distinct_on,
+                    _alias_ordered_group,
+                ]
             ),
             exp.StrToDate: lambda self, e: f"PARSE_DATE({self.format_time(e)}, {self.sql(e, 'this')})",
             exp.StrToTime: lambda self, e: f"PARSE_TIMESTAMP({self.format_time(e)}, {self.sql(e, 'this')})",

tests/dialects/test_bigquery.py

@@ -517,6 +517,16 @@ def test_bigquery(self):
             },
         )
 
+        self.validate_identity(
+            "SELECT y + 1 z FROM x GROUP BY y + 1 ORDER BY z",
+            "SELECT y + 1 AS z FROM x GROUP BY z ORDER BY z",
+        )
+        self.validate_identity(
+            "SELECT y + 1 z FROM x GROUP BY y + 1",
+            "SELECT y + 1 AS z FROM x GROUP BY y + 1",
+        )
+        self.validate_identity("SELECT y + 1 FROM x GROUP BY y + 1 ORDER BY 1")
+
     def test_user_defined_functions(self):
         self.validate_identity(
             "CREATE TEMPORARY FUNCTION a(x FLOAT64, y FLOAT64) RETURNS FLOAT64 NOT DETERMINISTIC LANGUAGE js AS 'return x*y;'"

tests/fixtures/optimizer/optimizer.sql

@@ -676,9 +676,9 @@ WHERE
   `top_terms`.`rank` = 1
   AND CAST(`top_terms`.`refresh_date` AS DATE) >= DATE_SUB(CURRENT_DATE, INTERVAL 2 WEEK)
 GROUP BY
-  `top_terms`.`refresh_date`,
-  `top_terms`.`term`,
-  `top_terms`.`rank`
+  `day`,
+  `top_term`,
+  `rank`
 ORDER BY
   `day` DESC;