Summary: in this tutorial, we will introduce you to the INTERSECT operator and show you how to emulate the MySQL INTERSECT operator.

Note that MySQL does not support the INTERSECT operator. This tutorial introduces you to how to emulate the INTERSECT operator in MySQL using join clauses.

Introduction to the INTERSECT operator

The INTERSECT operator is a set operator that returns only distinct rows of two queries or more queries.

The following illustrates the syntax of the INTERSECT operator.

Code language: SQL (Structured Query Language) (sql)

The INTERSECT operator compares the result sets of two queries and returns the distinct rows that are output by both queries.

To use the INTERSECT operator for two queries, you follow these rules:

1. The order and the number of columns in the select list of the queries must be the same.
2. The data types of the corresponding columns must be compatible.

The following diagram illustrates the INTERSECT operator.

The left query produces a result set of (1,2,3).

The right query returns a result set of (2,3,4).

The INTERSECT operator returns the distinct rows of both result sets which include (2,3).

Unlike the UNION operator, the INTERSECT operator returns the intersection between two circles.

Note that the SQL standard has three set operators that include UNION, INTERSECT, and MINUS.

Emulating INTERSECT in MySQL

Unfortunately, MySQL does not support the INTERSECT operator. However, you can emulate the INTERSECT operator.

Setting up sample tables

The following statements create tables t1 and t2, and then insert data into both tables.

Code language: SQL (Structured Query Language) (sql)

The following query returns rows from the t1 table.

Code language: SQL (Structured Query Language) (sql)

id
----
1
2
3

The following query returns the rows from the t2 table:

Code language: SQL (Structured Query Language) (sql)

id
---
2
3
4

1) Emulate INTERSECT using DISTINCT and INNER JOIN clause

The following statement uses DISTINCT operator and INNER JOIN clause to return the distinct rows in both tables:

Code language: SQL (Structured Query Language) (sql)

id
----
2
3

How it works.

1. The INNER JOIN clause returns rows from both left and right tables.
2. The DISTINCT operator removes the duplicate rows.

2) Emulate INTERSECT using IN and subquery

The following statement uses the IN operator and a subquery to return the intersection of the two result sets.

Code language: SQL (Structured Query Language) (sql)

id
----
2
3

How it works.

1. The subquery returns the first result set.
2. The outer query uses the IN operator to select only values that exist in the first result set. The DISTINCT operator ensures that only distinct values are selected.

In this tutorial, you have learned a couple of ways to simulate the INTERSECT operator in MySQL.