SQL Logical Operators

Introduction to SQL Logical Operators

SQL logical operators namely AND, OR and NOT are used to combine multiple conditions mentioned in the WHERE clause of the query to filter the rows from the resultant set obtained by the SELECT statement.

There are three different kinds of logical operators. They perform the following functions :

Logical Operator	Function
AND	Both the conditions mentioned in the WHERE clause should be TRUE.
OR	At least one of the conditions mentioned in the WHERE clause should be TRUE.
NOT	The mentioned condition should be false in the WHERE clause.

Syntax and parameters

The generic syntax for working with SQL logical operators is as follows :

SELECT column_name(s)
FROM table_name_1
WHERE condition_1 LOGICAL OPERATOR condition_2 LOGICAL OPERATOR condtion_3…;

The different parameters used in the syntax are :

SELECT column_name(s):  It is used to select the required data from the database. Mention the column name on which you want to perform the logical operation and want in the result set.

FROM table_name_1: Mention the table name from which the column has to be fetched.

WHERE condition_1: It is used to specify the conditions to filter records.

LOGICAL OPERATOR: Mention the type of logical operation you want to perform from {OR, AND} based on the conditions which you want the filtered rows to satisfy. The syntax for NOT operator is a bit different from AND and OR operators. We will discuss this when discussing NOT operator.

Of the above-mentioned parameters, all the parameters are mandatory. You may use GROUP BY, ORDER BY and HAVING clauses based on your requirement.

Going ahead we will be discussing the above mentioned logical operators in great detail.

In order to demonstrate and explain the Logical operators in SQL effectively, we will be using the following “Orders” table. This table is made for an e-commerce website. The table contains order id, customer names, city and the details of the items purchased by them.

The schema for the above mentioned “orders” table is :

Number of records: 15

Customers

Order_id(primary key)

Customer_name

City

Items_purchased

Amount_paid

Order_date

Let’s have a look at the records in the orders table. So that later, we can understand how logical operators are helpful:

Order_id	Customer_name	City	Items_purchased	Amount_paid	Order_date
1	Peter King	Manchester	Books	120	2020-01-13 00:00:00.000
2	Priya Krishna	New Delhi	pen	50	2020-01-12 00:00:00.000
3	Jim Halpert	Manchester	pencil	43	2020-02-13 00:00:00.000
4	Michael Scott	New York	Books	250	2020-02-10 00:00:00.000
5	Harvey Spector	Birmingham	pencil	100	2020-01-10 00:00:00.000
6	Deepa Kamat	Mumbai	Books	370	2019-12-13 00:00:00.000
7	Anita Desai	London	pencil	50	2019-12-01 00:00:00.000
8	Rachel Zane	Michigan	pen	70	2019-12-13 00:00:00.000
9	Petoria John	Canberra	pen	190	2020-01-13 00:00:00.000
10	John L	Budapest	Books	540	2020-01-13 00:00:00.000
11	Justin Green	Ottawa City	pen	65	2020-02-13 00:00:00.000
12	Babita Ghosh	Kolkata	pencil	75	2020-02-13 00:00:00.000
13	Krish Pratt	London	eraser	30	2019-12-01 00:00:00.000
14	Elizabeth Blunt	London	pencil	340	2019-12-01 00:00:00.000
15	Nina Debrov	Amsterdam	Books	452	2019-12-01 00:00:00.000
NULL	NULL	NULL	NULL	NULL	NULL

AND Logical Operator

SQL AND operator is used to combine two or more conditions mentioned in a WHERE clause of a query. Only those rows will be made to the final result set which satisfies all the mentioned conditions in the WHERE part of the statement.

Here are a few examples to illustrate the use of AND Operator.

Examples of SQL Logical Operators

Here are the following examples of SQL Logical Operators mention below

Example #1

Find the names of customers who have bought items in the pencil category and are from London.

Code:

SELECT Customer_name
FROM Orders
WHERE City = 'London' AND Items_purchased = 'pencil';

Example #2

Find the names of customers and their cities who have bought items in the books category and have spent more than 50 on an order.

Code:

SELECT Customer_name, City
FROM Orders
WHERE Items_purchased = 'pencil' AND Amount_paid > 50;

OR Logical Operator

SQL OR operator is used to combine two or more conditions mentioned in a WHERE clause of a query. Only those rows will be made to the final result set which satisfies at least one of the mentioned conditions in the WHERE part of the statement.

Here are a few examples to illustrate the use of OR Operator.

Example #3

Find the details of the order where customers have bought items in the pencil or pen category.

Code:

SELECT *
FROM Orders
WHERE Items_purchased = 'pencil' OR  Items_purchased = 'Pen';

Example #4

Find the names of customers who have bought items in the pencil or eraser category and are from London.

Code:

SELECT Customer_name
FROM Orders
WHERE Items_purchased = 'pencil' OR  Items_purchased = 'eraser' AND City = 'London';

NOT Logical Operator

SQL NOT operator is used to combine two or more conditions mentioned in the WHERE clause of a query. It is used to filter only those rows which do not meet the conditions mentioned in the WHERE part of the query.

The syntax for NOT operator is a bit different from AND and OR operators. It is as follows :

SELECT column_name(s) FROM table_name WHERE NOT condition;

Here are a few examples to illustrate the use of NOT Operator.

Example #5

Find the details of the order where customers have bought items, not in the pencil category.

Code:

SELECT *
FROM Orders
WHERE NOT Items_purchased = 'pencil';

Example #6

Find the details of orders in the books category which were not made in February.

Code:

SELECT *
FROM Orders
WHERE NOT MONTH(Order_date)='2' AND Items_purchased = 'Books';

Conclusion

As we have seen above, SQL logical operators are used to combine multiple conditions in a WHERE clause for filtering rows from the data set. AND, OR and NOT operations in SQL are similar to binary operations.

Recommended Articles

This is a guide to SQL Logical Operators. Here we discuss the examples of SQL Logical Operators along with the syntax and parameters. You may also have a look at the following articles to learn more –

1. SQL Clauses
2. SQL Set Operators
3. Custom SQL in Tableau
4. LIKE Query in SQL