Perform bitwise operations on column values

Understanding the MySQL BIT_XOR Function

In this tutorial, you'll learn how to use the MySQL BIT_XOR() function to perform a bitwise XOR operation on values in a column of a table.

What is the MySQL BIT_XOR() Function?

The BIT_XOR() function is an aggregate function in MySQL that applies a bitwise XOR (exclusive OR) operation on all values in a given column.

Syntax:

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SELECT BIT_XOR(column_name)
FROM table_name;

How Does BIT_XOR() Work?

The bitwise XOR operation compares corresponding bits of two numbers:

• If the bits are different (one is 1, the other is 0), the result is 1.
• If the bits are the same (both 0 or both 1), the result is 0.

Example of Bitwise XOR:

Let’s take two binary numbers:

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0101  (decimal 5)
0011  (decimal 3)
------
0110  (decimal 6)  <- Result of XOR

If there are more than two numbers, MySQL BIT_XOR() applies the XOR operation cumulatively across all values.

Special Cases:

• If there are no values in the column, BIT_XOR() returns 0.
• The output will have the same number of bits as the input values.

Example: Using BIT_XOR() in MySQL

Let's walk through an example to see how BIT_XOR() works in a real-world scenario.

Step 1: Create a Table

We'll create a devices table that stores binary status flags for different electronic devices.

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CREATE TABLE devices (
    device_id INT PRIMARY KEY,
    status_flags INT
);

• device_id is the unique identifier for each device.
• status_flags stores each device's status as an integer, which represents a binary value.

Step 2: Insert Sample Data

Now, let's insert some test data:

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INSERT INTO devices (device_id, status_flags)
VALUES
    (1, 6),   -- 6 in binary: 0110
    (2, 3),   -- 3 in binary: 0011
    (3, 5);   -- 5 in binary: 0101

Step 3: Use BIT_XOR() to Find Unique Status Flags

Now, we’ll apply the BIT_XOR() function to find the exclusive status flags across these devices:

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SELECT
  BIT_XOR(status_flags) AS exclusive_flags
FROM
  devices
WHERE
  device_id IN (1, 2, 3);

Understanding the Computation:

We apply the bitwise XOR operation across the three values:

1. 6 XOR 3 (0110 ⊕ 0011) → 0101 (Decimal 5)
2. 5 XOR 5 (0101 ⊕ 0101) → 0000 (Decimal 0)

Final Output:

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+-----------------+
| exclusive_flags |
+-----------------+
|               0 |
+-----------------+

Explanation of the Result:

• Since the final XOR result is 0, this means all bits cancel out across the selected devices.
• This suggests that each device has a combination of unique status flags, and no common bit is set across all values.

Summary

• The BIT_XOR() function performs a bitwise XOR operation on values in a column.
• It compares bits and returns 1 if they differ, 0 if they are the same.
• It’s useful for finding unique flags or checking whether all values share common bits.
• If the final result is 0, it means that the input values cancel each other out.

This function is particularly useful for status tracking, permissions handling, and feature flag analysis in databases. 🚀