In addition to the information that is displayed for standard Unity Catalog catalogs, Catalog Explorer also displays the Connection used by the foreign catalog and the external database or catalog that is mirrored by the foreign catalog.
Run read-only queries on tables in foreign catalogs: see Query data.
When you write queries in Databricks, you must use Apache Spark data types. For a mapping of Spark data types to your external database data types, see the article for your connection type, listed in the table of contents in the left navigation pane of this documentation site.