In MySQL, the OCT() function is used for converting from decimal to octal.

More precisely, it returns a string representation of the octal value of its argument.

Syntax

The basic syntax goes like this:

OCT(N)

Where n is the value to be converted. This argument is a longlong (BIGINT) number.

Example 1 – Basic Usage

Here’s an example of how it works:

SELECT OCT(8);

Result:

+--------+
| OCT(8) |
+--------+
| 10     |
+--------+

The result is 10 because that is the octal equivalent of 8 from the decimal system.

Example 2 – Various Values

Here’s another example with various values:

SELECT 
  OCT(10),
  OCT(20),
  OCT(30),
  OCT(100),
  OCT(1000);

Result:

+---------+---------+---------+----------+-----------+
| OCT(10) | OCT(20) | OCT(30) | OCT(100) | OCT(1000) |
+---------+---------+---------+----------+-----------+
| 12      | 24      | 36      | 144      | 1750      |
+---------+---------+---------+----------+-----------+

Example 3 – Expressions

You can also use expressions like the ones below:

SELECT 
  OCT(100 + 2),
  OCT(100 * 2),
  OCT(100 / 2),
  OCT(100 - 2);

Result:

+--------------+--------------+--------------+--------------+
| OCT(100 + 2) | OCT(100 * 2) | OCT(100 / 2) | OCT(100 - 2) |
+--------------+--------------+--------------+--------------+
| 146          | 310          | 62           | 142          |
+--------------+--------------+--------------+--------------+

What is Octal?

Octal is a system of numerical notation that has 8 as a base.  This is in contrast to decimal, which has 10 as a base.

In decimal, we count up to 9, then start again by adding a zero after the first digit (e.g. after 9 comes 10, which is 1 with a zero added to it).

In octal (base 8) however, we only count to 7 before starting again and adding a zero. So 10 in octal is the equivalent of 8 in decimal.

Here’s a table to demonstrate:

Decimal (Base 10)	Octal (Base 8)
1	1
2	2
3	3
4	4
5	5
6	6
7	7
8	10
9	11
10	12
11	13
12	14
13	15
14	16
15	17
16	20
17	21
18	22
19	23
20	24