How Can I Perform SQL INTERSECT and MINUS Operations in Microsoft Access?

Implementing SQL INTERSECT and MINUS Operations in Microsoft Access

Intersecting and subtracting tables, represented by the INTERSECT and MINUS operators in SQL, can be challenging in Microsoft Access. Fortunately, these operations can be achieved using inner and outer joins, respectively.

INTERSECT: An Inner Join

To perform an INTERSECT operation, use an inner join. This join returns only the rows where the join condition matches in both participating tables. The following query demonstrates an INTERSECT operation:

select distinct
  a.*
from
  a
  inner join b on a.id = b.id

This query retrieves all rows from table a that have matching rows in table b. The distinct keyword eliminates duplicate rows.

MINUS: An Outer Join

MINUS, or an outer join, returns rows from a specified table that do not have matching rows in another table. In Access, a left outer join can be used to achieve this:

select distinct
  a.*
from
  a
  left outer join b on a.id = b.id
where
  b.id is null

This query fetches all rows from table a that do not have corresponding rows in table b. The left outer join retrieves all rows from a, regardless of whether they have matches in b. The where clause filters out the rows with matches.

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