Fix(bigquery): MOD edge case

sqlglot/dialects/bigquery.py

@@ -609,7 +609,6 @@ class Generator(generator.Generator):
             exp.IntDiv: rename_func("DIV"),
             exp.JSONFormat: rename_func("TO_JSON_STRING"),
             exp.Max: max_or_greatest,
-            exp.Mod: lambda self, e: self.func("MOD", e.this.unnest(), e.expression.unnest()),
             exp.MD5: lambda self, e: self.func("TO_HEX", self.func("MD5", e.this)),
             exp.MD5Digest: rename_func("MD5"),
             exp.Min: min_or_least,
@@ -801,6 +800,15 @@ class Generator(generator.Generator):
             "within",
         }
 
+        def mod_sql(self, expression: exp.Mod) -> str:
+            this = expression.this
+            expr = expression.expression
+            return self.func(
+                "MOD",
+                this.unnest() if isinstance(this, exp.Paren) else this,
+                expr.unnest() if isinstance(expr, exp.Paren) else expr,
+            )
+
         def column_parts(self, expression: exp.Column) -> str:
             if expression.meta.get("quoted_column"):
                 # If a column reference is of the form `dataset.table`.name, we need

tests/dialects/test_bigquery.py

@@ -1470,6 +1470,7 @@ def test_mod(self):
             with self.subTest(f"Testing BigQuery roundtrip of modulo operation: {sql}"):
                 self.validate_identity(sql)
 
+        self.validate_identity("SELECT MOD((SELECT 1), 2)")
         self.validate_identity(
             "MOD((a + 1), b)",
             "MOD(a + 1, b)",