SQL Server System functions

A set of built-in functions that perform operations on values, objects, and settings in SQL Server and return information about them. datalength (expression)

system functions	functions
app_name ()	returns the application name of the current session (if the application is set)
CASE Expression	evaluates a list of conditions and returns one of several possible results of an expression
CAST (expression as data_type)	Convert expression display to another data type
convert (data_type[(length)],expression[,style])	Converts an expression display to another data type. Cast and convert provide similar functionality
COALESCE (expression[,..., n])	returns the first non-empty expression in a list
returns the number of bytes consumed by the expression
host_name ()	return host name
ISDATE (expression)	returns 1 if the expression is in valid date format, otherwise 0
ISNULL (check_expression,replacement_value)	expression value is null, replace with the specified replacement value
isnumeric (expression)	Determines whether an expression is a numeric type, returns 1, or returns 0
NEWID	generate globally unique identifiers
nullif	returns a null value if the two specified expressions are equal

SQL Server System functions