There are three main types of SQL-specific query: union queries, pass-through queries, and data-definition queries.

Union queries combine data from two or more tables, but not in the same manner as other queries. Whereas most queries combine data by concatenating rows, union queries combine data by appending rows. Union queries differ from append queries in that union queries do not change the underlying tables. Union queries append the rows in a recordset that does not persist after the query is closed.

Pass-through queries are not processed by the database engine that comes with Access; rather, they are passed directly to a remote database server that does the processing and then passes the results back to Access.

Data-definition queries are a special type of query that does not process data; instead, data-definition queries create, delete or modify other database objects.

SQL-specific queries cannot be opened in Design view. They can only be opened in SQL view, or run. Except for data-definition queries, running a SQL-specific query opens it in Datasheet view.