fix: apply suggestions from code review

Co-authored-by: Jo <46752250+georgesittas@users.noreply.github.com>

Author: MisterWheatley

sqlmesh/core/engine_adapter/risingwave.py

@@ -53,10 +53,8 @@ def columns(
             )
         )
 
-        if table.args.get("db"):
-            sql = sql.where(
-                exp.column("name", table="rw_schemas", quoted=False).eq(table.args["db"].name)
-            )
+        if table.db:
+            sql = sql.where(exp.column("name", table="rw_schemas").eq(table.db))
 
         self.execute(sql)
         resp = self.cursor.fetchall()

tests/core/engine_adapter/integration/test_integration_risingwave.py

@@ -70,16 +70,11 @@ def test_engine_adapter_columns(
     ctx: TestContext, risingwave_columns_with_datatypes: t.Dict[str, exp.DataType]
 ):
     table = ctx.table("TEST_COLUMNS")
-    query_cols: t.List[str] = [
-        f"NULL::{data_type.sql(dialect='risingwave')} AS {col_name}"
-        for col_name, data_type in risingwave_columns_with_datatypes.items()
-    ]
-    query: exp.Query = exp.maybe_parse(
-        f"""
-        SELECT
-          {",".join(query_cols)}
-        """,
-        dialect="risingwave",
+    query = exp.select(
+        *[
+            exp.cast(exp.null(), dtype).as_(name)
+            for name, dtype in risingwave_columns_with_datatypes.items()
+        ]
     )
     ctx.engine_adapter.ctas(table, query)