Base 64 in SQL Server
Base 64 encoding is the process of converting bytes (8 bits) to readable, printable characters. To do this, 64 possible characters are used (6 bits), and every 3 bytes translates into 4 characters.
SQL Server generally shouldn’t need to do this. - storing binary in the database is just fine - but if you need it, here’s one way to do it.
There’s another XML function you could do, something like xs:base64Binary - or you could also use a CLR function - but this is a pretty easy way to go.