If you were moving MSSQL into SAP, there are several examples available of using Cast or Convert to change an MSSQL datetime to a date. You could use this in your SQL Statement.
However, you're going the other way, from SAP into MS SQL. For that, the SAP Help has an example of assembling sy-datum and sy-uzeit into a whole timestamp using Convert.
Reference:
http://help.sap.com/saphelp_nwpi71/helpdata/en/52/491a40251e2402e10000000a1550b0/content.htm
Obviously, this is something that would be done outside of LEI.