How the BIT_COUNT() function works in Mariadb?

MariaDB’s BIT_COUNT() function is used to count the number of bits set to 1 in a given integer.

Posted on

The MariaDB BIT_COUNT() function is used to count the number of bits set to 1 in a given integer. This function is useful for scenarios such as analyzing binary data, counting flags in bitmasks, or simply understanding the composition of binary values.

Syntax

The syntax for the MariaDB BIT_COUNT() function is as follows:

BIT_COUNT(N)

This function accepts a single argument N, which is an integer, and returns the count of bits set to 1.

Examples

Example 1: Counting Bits in a Number

This example demonstrates how to count the number of bits set to 1 in the number 5:

SELECT BIT_COUNT(5);

+--------------+
| BIT_COUNT(5) |
+--------------+
|            2 |
+--------------+

The output is 2 because the binary representation of 5 is 101, which has two bits set to 1.

Example 2: Counting Bits in Zero

Here we’ll see the result of counting bits in 0:

SELECT BIT_COUNT(0);

+--------------+
| BIT_COUNT(0) |
+--------------+
|            0 |
+--------------+

The output is 0 because there are no bits set to 1 in the binary representation of 0.

Example 3: Counting Bits in a Negative Number

This example shows the bit count for a negative number:

SELECT BIT_COUNT(-1);

+---------------+
| BIT_COUNT(-1) |
+---------------+
|            64 |
+---------------+

The output is 64 because, in a 64-bit system, the binary representation of -1 is all bits set to 1.

Example 4: Using with a Table

To use BIT_COUNT() with table data, let’s create a simple table:

DROP TABLE IF EXISTS example;
CREATE TABLE example (a INT);
INSERT INTO example VALUES (5), (0), (-1);

Now, let’s count the bits:

SELECT a, BIT_COUNT(a) FROM example;

+------+--------------+
| a    | BIT_COUNT(a) |
+------+--------------+
|    5 |            2 |
|    0 |            0 |
|   -1 |           64 |
+------+--------------+

The output shows the bit counts for each value in column a.

Example 5: Counting Bits in a Large Number

Let’s count the bits set to 1 in a large number:

SELECT BIT_COUNT(123456789);

+----------------------+
| BIT_COUNT(123456789) |
+----------------------+
|                   16 |
+----------------------+

The output is 16 because the binary representation of 123456789 has sixteen bits set to 1.

Here are a few functions related to MariaDB’s BIT_COUNT():

  • MariaDB’s BIT_AND() function is used to perform a bitwise AND operation on all bits in an expression.
  • MariaDB’s BIT_OR() function is used to perform a bitwise OR operation on all bits in an expression.
  • MariaDB’s BIT_XOR() function is used to perform a bitwise XOR operation on all bits in an expression.

Conclusion

The BIT_COUNT() function in MariaDB is a straightforward yet powerful tool for working with binary data. It allows for efficient analysis of bit patterns and can be used in a variety of applications, from data analysis to system programming. Understanding its usage and related functions can enhance your database querying capabilities.