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SQL: INTERSECT Operator

Learn how to use the SQL INTERSECT operator with syntax and examples.

Description

The SQL INTERSECT operator is used to return the results of 2 or more SELECT statements. 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 must have the same number of fields in the result sets with similar data types.

Syntax

The syntax for the SQL INTERSECT operator is:

SELECT field1, field2, ... field_n
FROM tables
INTERSECT
SELECT field1, field2, ... field_n
FROM tables;

Example - With Single field

The following is a SQL INTERSECT operator example that has one field with the same data type:

SELECT supplier_id
FROM suppliers
INTERSECT
SELECT supplier_id
FROM orders;

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

Example - Using ORDER BY

The following is an INTERSECT example that uses a 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 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.