The datetime conversions (SQL Server) include the following functions :
The Convert function is a good general choice but DateName and DatePart provide flexibility.
SET DATEFORMAT dmy is used
SELECT CAST('7/31/2013' AS DateTime)
You can also use different styles to convert to and from text:
SELECT CONVERT(VARCHAR, CONVERT(DATETIME, '31-Jul-2013', 106), 106)
will display 31 Jul 2013
The allowed  styles include 0, 100 Default:mon dd yyyy hh:mi AM (or PM)
Style 101 : USA mm/dd/yyyy
Style 102 : ANSI yyyy. mm. dd
Style 103 : British /French dd/mm/yyyy
Style 104: German dd.mm.yyyy
Style 105: Italian dd-mm-yyyy
Style 106: dd mon yyyy
Style 107: mon dd, yyyy
Style 108 : hh:mm:ss
Style 9, 109:  Default with milliseconds
Style 110 USA:mm-dd-yyyy
Style 111 : Japan: yyyy/mm/dd
Style 112: ISO:yyyymmdd
Style 13, 113: Europe default with milliseconds  and 24hour clock
Style 114: hh:mm:ss:mmm with a 24 hour clock
Style 20, 120 ODBC canonical, 24 hour clock: yyyy-mm-dd hh:mi:ss
Style 21, 121 ODBC canonical with milliseconds, 24 hour clock:yyyy-mm-dd hh:mi:ss.mmm