FromBase64String Function The FromBase64String() function takes one (1) argument of base 64 encoded binary string and returns the string value. The syntax for FromBase64String function is FromBase64String( Base 64 String Value ). /* Following will produce SQLDatabase.Net */ SELECT FromBase64String('U1FMRGF0YWJhc2UuTmV0') ; Base 64 strings are used to transfer data over the internet and to generate small hash of value.