SQL > Advanced SQL > Intersect

The INTERSECT command in SQL combines the results of two SQL statement and returns only data that are present in both SQL statements.

INTERSECT can be thought of as an AND operator (value is selected only if it appears in both statements), while UNION and UNION ALL can be thought of as an OR operator (value is selected if it appears in either the first or the second statement).

Syntax

The syntax for INTERSECT is as follows:

[SQL Statement 1]
INTERSECT
[SQL Statement 2];

The columns selected in [SQL Statement 1] and [SQL Statement 2] need to be of the same data type for INTERSECT to work.

Example

We use the following tables for our example.

Table Store_Information

Store_NameSalesTxn_Date
Los Angeles1500Jan-05-1999
San Diego250Jan-07-1999
Los Angeles300Jan-08-1999
Boston700Jan-08-1999

Table Internet_Sales

Txn_DateSales
Jan-07-1999250
Jan-10-1999535
Jan-11-1999320
Jan-12-1999750

To find out all the dates where there are both store sales and internet sales, we use the following SQL statement:

SELECT Txn_Date FROM Store_Information
INTERSECT
SELECT Txn_Date FROM Internet_Sales;

Result:

Txn_Date
Jan-07-1999

Please note that the INTERSECT command will only return distinct values.

Next: SQL MINUS




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