**Summary**: in this tutorial, you will learn how to use the Oracle `INTERSECT`

operator to compare two queries and returns rows that are output by both.

## Introduction to Oracle `INTERSECT`

operator

The Oracle `INTERSECT`

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

The following statement shows the syntax of the `INTERSECT`

operator:

```
SELECT
column_list_1
FROM
T1
INTERSECT
SELECT
column_list_2
FROM
T2;
```

Similar to the `UNION`

operator, you must follow these rules when using the `INTERSECT`

operator:

- The number and the order of columns must be the same in the two queries.
- The data type of the corresponding columns must be in the same data type group such as numeric or character.

## Oracle `INTERSECT`

illustration

Suppose we have two queries that return the T1 and T2 result set.

- T1 result set includes 1, 2, 3.
- T2 result set includes 2, 3, 4.

The intersect of T1 and T2 result returns 2 and 3. Because these are distinct values that are output by both queries.

The following picture illustrates the intersection of T1 and T2:

The illustration showed that the `INTERSECT`

returns the intersection of two circles (or sets).

## Oracle `INTERSECT`

example

See the following `contacts`

and `employees`

tables in the sample database.

The following statement uses the `INTERSECT`

operator to get the last names used by people in both `contacts`

and `employees`

tables:

```
SELECT
last_name
FROM
contacts
INTERSECT
SELECT
last_name
FROM
employees
ORDER BY
last_name;
```

Note that we placed the `ORDER BY`

clause at the last queries to sort the result set returned by the `INTERSECT`

operator.

In this tutorial, you have learned how to use the Oracle `INTERSECT`

operator to compare two queries and returns the distinct rows that are output by both queries.