Summary: in this tutorial, you will learn how to use the MySQL BIT_OR()
function to perform a bitwise OR operation on the values of a column in a table.
Introduction to MySQL BIT_OR() function
The BIT_OR()
function is an aggregate function that performs a bitwise OR operation on values in a column of a table.
The bitwise OR takes two-bit patterns of equal length and performs the logical inclusive OR on each pair of corresponding bits. It returns 0 if both bits are 0, otherwise it returns 1.
For example, the following illustrates how to perform a bitwise OR on the 0101 (decimal 5) and 0011 (decimal 3), which results in 0111 (decimal 7):
0101 (decimal 5)
0011 (decimal 3)
----
0111 (decimal 7)
Here’s the basic syntax of the BIT_OR
function:
SELECT BIT_OR(column_name)
FROM table_name;
Code language: SQL (Structured Query Language) (sql)
In practice, you’ll use the BIT_OR
function to manipulate data at the bit level such as permission systems.
MySQL BIT_OR() function example
First, create a new table called permissions
that has two columns user_id
and permission_flags
:
CREATE TABLE permissions (
user_id INT PRIMARY KEY,
permission_flags INT
);
Code language: SQL (Structured Query Language) (sql)
In this table, the user_id
uniquely identifies each user and permission_flags
stores the user’s permissions flags as binary values.
Second, insert some rows into the permissions
table:
INSERT INTO permissions (user_id, permission_flags)
VALUES
(1, 6), -- Binary: 0110
(2, 3), -- Binary: 0011
(3, 5); -- Binary: 0101
Code language: SQL (Structured Query Language) (sql)
Third, determine the collective permission of users with id 1 and 2 by using the BIT_OR
function to combine permission flags:
SELECT
BIT_OR(permission_flags) AS collective_permissions
FROM
permissions
WHERE
user_id IN (1, 2);
Code language: SQL (Structured Query Language) (sql)
Output:
+------------------------+
| collective_permissions |
+------------------------+
| 7 |
+------------------------+
1 row in set (0.00 sec)
Code language: SQL (Structured Query Language) (sql)
When we apply the bitwise OR operation, the result will be 0111
, which corresponds to the decimal value 7.
This means that the collective permissions for users 1 and 2 include the permission flags for reading, writing, and possibly other permissions (depending on your specific flag definitions).
Summary
- Use MySQL
BIT_OR
to perform bitwise operations on values in a columns of table.