In MariaDB, CONV() is a built-in numeric function that converts numbers between different number bases. For example, you can use it to convert a number from base 10 to base 16.

It returns a string representation of the converted number.

Syntax

The syntax goes like this:

CONV(N,from_base,to_base)

Where N is the number to convert, from_base is the base to convert from, and to_base is the base to convert to.

The minimum base is 2 and the maximum base is 36.

Example

Here’s an example:

SELECT CONV(12, 10, 16);

Result:

+------------------+
| CONV(12, 10, 16) |
+------------------+
| C                |
+------------------+

The result is C because that’s the hexadecimal (base 16) value for 12.

So the count goes like this: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C.

Here’s another one:

SELECT CONV(1234567, 10, 16);

Result:

+-----------------------+
| CONV(1234567, 10, 16) |
+-----------------------+
| 12D687                |
+-----------------------+

Negative Base

If the to_base argument is a negative number, N is regarded as a signed number. Otherwise it’s treated as unsigned.

SELECT CONV(-12, 10, -16);

Result:

+--------------------+
| CONV(-12, 10, -16) |
+--------------------+
| -C                 |
+--------------------+

Out of Range Base

The minimum base is 2 and the maximum base is 36. If the second or third argument isn’t within this range, null is returned.

Example

SELECT CONV(12, 10, 42);

Result:

+------------------+
| CONV(12, 10, 42) |
+------------------+
| NULL             |
+------------------+

String Arguments

The number is interpreted as an integer, but may be specified as an integer or a string. 

SELECT CONV('C', 16, 2);

Result:

+------------------+
| CONV('C', 16, 2) |
+------------------+
| 1100             |
+------------------+

Null Arguments

CONV() returns null if any of the arguments are null:

SELECT CONV(null, 10, 8);

Result:

+-------------------+
| CONV(null, 10, 8) |
+-------------------+
| NULL              |
+-------------------+

Missing Arguments

Calling CONV() with the wrong number of arguments, or without any arguments results in an error:

SELECT CONV();

Result:

ERROR 1582 (42000): Incorrect parameter count in the call to native function 'CONV'

And:

SELECT CONV(10, 2);

Result:

ERROR 1582 (42000): Incorrect parameter count in the call to native function 'CONV'