ToBase64String Function The ToBase64String() function takes one (1) argument and returns base 64 encoded binary string. The syntax for ToBase64String function is ToBase64String( Value ). /* Following will produce U1FMRGF0YWJhc2UuTmV0 */ SELECT ToBase64String('SQLDatabase.Net') ; Base 64 strings are used to transfer data over the internet and to generate small hash of given value.