INTERSECT Query

The SQL INTERSECT query allows you to return the results of 2 or more "select" queries. However, it only returns the rows selected by all queries. If a record exists in one query and not in the other, it will be omitted from the INTERSECT results.

Each SQL statement within the SQL INTERSECT query must have the same number of fields in the result sets with similar data types.

The syntax for the SQL INTERSECT query is:

select field1, field2, . field_n
from tables
INTERSECT
select field1, field2, . field_n
from tables;

SQL INTERSECT Query - Single field example

The following is an example of an SQL INTERSECT query that has one field with the same data type:

select supplier_id
from suppliers
INTERSECT
select supplier_id
from orders;

In this SQL INTERSECT query example, if a supplier_id appeared in both the suppliers and orders table, it would appear in your result set.

SQL INTERSECT Query - Using ORDER BY Clause example

The following is an SQL INTERSECT query that uses an SQL ORDER BY clause:

select supplier_id, supplier_name
from suppliers
where supplier_id > 2000
INTERSECT
select company_id, company_name
from companies
where company_id > 1000
ORDER BY 2;

Since the column names are different between the two "select" statements, it is more advantageous to reference the columns in the SQL ORDER BY clause by their position in the result set. In this example, we've sorted the results by supplier_name / company_name in ascending order, as denoted by the "ORDER BY 2".

The supplier_name / company_name fields are in position #2 in the result set.