SQL: 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.