Fix exist subquery when create materializer view

dbms/src/Storages/StorageMaterializedView.cpp

@@ -44,9 +44,14 @@ static void extractDependentTable(const ASTSelectQuery & query, String & select_
         select_database_name = typeid_cast<const ASTIdentifier &>(*query_database).name;
         select_table_name = ast_id->name;
     }
-    else if (auto ast_select = typeid_cast<const ASTSelectQuery *>(query_table.get()))
+    else if (auto ast_select = typeid_cast<const ASTSelectWithUnionQuery *>(query_table.get()))
     {
-        extractDependentTable(*ast_select, select_database_name, select_table_name);
+        if (ast_select->list_of_selects->children.size() != 1)
+            throw Exception("UNION is not supported for MATERIALIZED VIEW", ErrorCodes::INCORRECT_QUERY);
+
+        auto inner_query = ast_select->list_of_selects->children.at(0);
+
+        extractDependentTable(typeid_cast<const ASTSelectQuery &>(*inner_query), select_database_name, select_table_name);
     }
     else
         throw Exception("Logical error while creating StorageMaterializedView."