Fix(clickhouse)!: use creatable kind mapping dict for schema<-->datab…

…ase substitution (#3924)

* Transpile schema to database in drop statements

* Use kind mapping dict instead of method overrides

sqlglot/dialects/clickhouse.py

@@ -120,6 +120,8 @@ class ClickHouse(Dialect):
         "\\0": "\0",
     }
 
+    CREATABLE_KIND_MAPPING = {"DATABASE": "SCHEMA"}
+
     class Tokenizer(tokens.Tokenizer):
         COMMENTS = ["--", "#", "#!", ("/*", "*/")]
         IDENTIFIERS = ['"', "`"]
@@ -444,15 +446,6 @@ def _parse_types(
 
             return dtype
 
-        def _parse_create(self) -> exp.Create | exp.Command:
-            create = super()._parse_create()
-
-            # DATABASE in ClickHouse is the same as SCHEMA in other dialects
-            if isinstance(create, exp.Create) and create.kind == "DATABASE":
-                create.set("kind", "SCHEMA")
-
-            return create
-
         def _parse_extract(self) -> exp.Extract | exp.Anonymous:
             index = self._index
             this = self._parse_bitwise()
@@ -1046,10 +1039,6 @@ def create_sql(self, expression: exp.Create) -> str:
             else:
                 comment_prop = None
 
-            # ClickHouse only has DATABASEs and objects under them, eg. TABLEs, VIEWs, etc
-            if expression.kind == "SCHEMA":
-                expression.set("kind", "DATABASE")
-
             create_sql = super().create_sql(expression)
 
             comment_sql = self.sql(comment_prop)

sqlglot/dialects/dialect.py

@@ -133,6 +133,10 @@ def __new__(cls, clsname, bases, attrs):
         klass.INVERSE_FORMAT_MAPPING = {v: k for k, v in klass.FORMAT_MAPPING.items()}
         klass.INVERSE_FORMAT_TRIE = new_trie(klass.INVERSE_FORMAT_MAPPING)
 
+        klass.INVERSE_CREATABLE_KIND_MAPPING = {
+            v: k for k, v in klass.CREATABLE_KIND_MAPPING.items()
+        }
+
         base = seq_get(bases, 0)
         base_tokenizer = (getattr(base, "tokenizer_class", Tokenizer),)
         base_jsonpath_tokenizer = (getattr(base, "jsonpath_tokenizer_class", JSONPathTokenizer),)
@@ -384,6 +388,12 @@ class Dialect(metaclass=_Dialect):
     dialects which don't support fixed size arrays such as Snowflake, this should be interpreted as a subscript/index operator
     """
 
+    CREATABLE_KIND_MAPPING: dict[str, str] = {}
+    """
+    Helper for dialects that use a different name for the same creatable kind. For example, the Clickhouse
+    equivalent of CREATE SCHEMA is CREATE DATABASE.
+    """
+
     # --- Autofilled ---
 
     tokenizer_class = Tokenizer
@@ -400,6 +410,8 @@ class Dialect(metaclass=_Dialect):
     INVERSE_FORMAT_MAPPING: t.Dict[str, str] = {}
     INVERSE_FORMAT_TRIE: t.Dict = {}
 
+    INVERSE_CREATABLE_KIND_MAPPING: dict[str, str] = {}
+
     ESCAPED_SEQUENCES: t.Dict[str, str] = {}
 
     # Delimiters for string literals and identifiers

sqlglot/expressions.py

@@ -2001,6 +2001,11 @@ class Drop(Expression):
         "cluster": False,
     }
 
+    @property
+    def kind(self) -> t.Optional[str]:
+        kind = self.args.get("kind")
+        return kind and kind.upper()
+
 
 class Filter(Expression):
     arg_types = {"this": True, "expression": True}

sqlglot/generator.py

@@ -980,6 +980,7 @@ def createable_sql(self, expression: exp.Create, locations: t.DefaultDict) -> st
 
     def create_sql(self, expression: exp.Create) -> str:
         kind = self.sql(expression, "kind")
+        kind = self.dialect.INVERSE_CREATABLE_KIND_MAPPING.get(kind) or kind
         properties = expression.args.get("properties")
         properties_locs = self.locate_properties(properties) if properties else defaultdict()
 
@@ -1278,6 +1279,7 @@ def drop_sql(self, expression: exp.Drop) -> str:
         expressions = self.expressions(expression, flat=True)
         expressions = f" ({expressions})" if expressions else ""
         kind = expression.args["kind"]
+        kind = self.dialect.INVERSE_CREATABLE_KIND_MAPPING.get(kind) or kind
         exists_sql = " IF EXISTS " if expression.args.get("exists") else " "
         on_cluster = self.sql(expression, "cluster")
         on_cluster = f" {on_cluster}" if on_cluster else ""

sqlglot/parser.py

@@ -1665,7 +1665,7 @@ def _parse_drop(self, exists: bool = False) -> exp.Drop | exp.Command:
         temporary = self._match(TokenType.TEMPORARY)
         materialized = self._match_text_seq("MATERIALIZED")
 
-        kind = self._match_set(self.CREATABLES) and self._prev.text
+        kind = self._match_set(self.CREATABLES) and self._prev.text.upper()
         if not kind:
             return self._parse_as_command(start)
 
@@ -1687,7 +1687,7 @@ def _parse_drop(self, exists: bool = False) -> exp.Drop | exp.Command:
             exists=if_exists,
             this=table,
             expressions=expressions,
-            kind=kind.upper(),
+            kind=self.dialect.CREATABLE_KIND_MAPPING.get(kind) or kind,
             temporary=temporary,
             materialized=materialized,
             cascade=self._match_text_seq("CASCADE"),
@@ -1850,11 +1850,12 @@ def extend_props(temp_props: t.Optional[exp.Properties]) -> None:
         if self._curr and not self._match_set((TokenType.R_PAREN, TokenType.COMMA), advance=False):
             return self._parse_as_command(start)
 
+        create_kind_text = create_token.text.upper()
         return self.expression(
             exp.Create,
             comments=comments,
             this=this,
-            kind=create_token.text.upper(),
+            kind=self.dialect.CREATABLE_KIND_MAPPING.get(create_kind_text) or create_kind_text,
             replace=replace,
             refresh=refresh,
             unique=unique,

tests/dialects/test_clickhouse.py

@@ -672,6 +672,16 @@ def test_ddl(self):
                 "duckdb": "CREATE SCHEMA x",
             },
         )
+        self.validate_all(
+            "DROP DATABASE x",
+            read={
+                "duckdb": "DROP SCHEMA x",
+            },
+            write={
+                "clickhouse": "DROP DATABASE x",
+                "duckdb": "DROP SCHEMA x",
+            },
+        )
         self.validate_all(
             """
             CREATE TABLE example1 (