MySQL:

CONV

Syntax:
CONV(N,from_base,to_base)

Converts numbers between different number bases. Returns a string
representation of the number N, converted from base from_base to base
to_base. Returns NULL if any argument is NULL. The argument N is
interpreted as an integer, but may be specified as an integer or a
string. The minimum base is 2 and the maximum base is 36. If from_base
is a negative number, N is regarded as a signed number. Otherwise, N is
treated as unsigned. CONV() works with 64-bit precision.

Example

mysql> SELECT CONV('a',16,2);
-> '1010'
mysql> SELECT CONV('6E',18,8);
-> '172'
mysql> SELECT CONV(-17,10,-18);
-> '-H'
mysql> SELECT CONV(10+'10'+'10'+X'0a',10,10);
-> '40'