As mentioned earlier, we can also use the functions in your SELECT statements. SQL Server 2014 comes with many built-in functions (also known as system functions), and also lets you create user-defined functions. The functions are either deterministic or nondeterministic. The deterministic functions return the same value every time, while nondeterministic functions might return different values each time based on the values of their specified input parameters. The SQL Server 2014 built-in functions belong to one of the following categories:
Aggregate functions
Configuration functions
Cursor functions
Date and time functions
Mathematical functions
Metadata functions
Other functions
Rowset functions
Security functions
String functions
System statistical functions