chore(exasol): transformed rank function, ignoring parameters (#6408)

* chore: custom transformed rank function in exasol ensuring parameters are ignored

* chore(exasol): refactored implementation, ignoring arguments

Author: nnamdi16

sqlglot/dialects/exasol.py

@@ -417,3 +417,9 @@ def dateadd_sql(self, expression: exp.DateAdd) -> str:
                 return self.function_fallback_sql(expression)
 
             return self.func(f"ADD_{unit}S", expression.this, expression.expression)
+
+        # https://docs.exasol.com/db/latest/sql_references/functions/alphabeticallistfunctions/rank.htm
+        def rank_sql(self, expression: exp.Rank) -> str:
+            if expression.args.get("expressions"):
+                self.unsupported("Exasol does not support arguments in RANK")
+            return self.func("RANK")

tests/dialects/test_exasol.py

@@ -218,6 +218,15 @@ def test_aggregateFunctions(self):
             },
         )
 
+        self.validate_all(
+            "SELECT a, b, rank(b) OVER (ORDER BY b) FROM (VALUES ('A1', 2), ('A1', 1), ('A2', 3), ('A1', 1)) AS tab(a, b)",
+            write={
+                "exasol": "SELECT a, b, RANK() OVER (ORDER BY b) FROM (VALUES ('A1', 2), ('A1', 1), ('A2', 3), ('A1', 1)) AS tab(a, b)",
+                "databricks": "SELECT a, b, RANK(b) OVER (ORDER BY b NULLS LAST) FROM VALUES ('A1', 2), ('A1', 1), ('A2', 3), ('A1', 1) AS tab(a, b)",
+                "spark": "SELECT a, b, RANK(b) OVER (ORDER BY b NULLS LAST) FROM VALUES ('A1', 2), ('A1', 1), ('A2', 3), ('A1', 1) AS tab(a, b)",
+            },
+        )
+
     def test_stringFunctions(self):
         self.validate_identity(
             "TO_CHAR(CAST(TO_DATE(date, 'YYYYMMDD') AS TIMESTAMP), 'DY') AS day_of_week"