When you convert expressions from one type to another, in many cases there will be a need within a stored procedure or other routine to convert data from a datetime type to a varchar type. The Convert function is used for such things. The CONVERT() function can be used to display date/time data in various formats. Syntax
CONVERT(data_type(length), expression, style)
Style - style values for datetime or smalldatetime conversion to character data. Add 100 to a style value to get a four-place year that includes the century (yyyy).
select convert(varchar(20),GETDATE(),108) 13:27:16