Fix(clickhouse)!: parse parameter key as Var instead of Identifier (#4888)

Author: georgesittas

sqlglot/dialects/clickhouse.py

@@ -609,6 +609,9 @@ def _parse_query_parameter(self) -> t.Optional[exp.Expression]:
             elif not self._match(TokenType.R_BRACE):
                 self.raise_error("Expecting }")
 
+            if isinstance(this, exp.Identifier) and not this.quoted:
+                this = exp.var(this.name)
+
             return self.expression(exp.Placeholder, this=this, kind=kind)
 
         def _parse_bracket(

tests/dialects/test_clickhouse.py

@@ -3,6 +3,7 @@
 from sqlglot.dialects import ClickHouse
 from sqlglot.expressions import convert
 from sqlglot.optimizer import traverse_scope
+from sqlglot.optimizer.qualify_columns import quote_identifiers
 from tests.dialects.test_dialect import Validator
 from sqlglot.errors import ErrorLevel
 
@@ -11,6 +12,9 @@ class TestClickhouse(Validator):
     dialect = "clickhouse"
 
     def test_clickhouse(self):
+        expr = quote_identifiers(self.parse_one("{start_date:String}"), dialect="clickhouse")
+        self.assertEqual(expr.sql("clickhouse"), "{start_date: String}")
+
         for string_type_enum in ClickHouse.Generator.STRING_TYPE_MAPPING:
             self.validate_identity(f"CAST(x AS {string_type_enum.value})", "CAST(x AS String)")