parameters doubts

Hello,


First of all I thank the help you may offer.


I explain:


I have a transformation that is very simple: make a select from a table and insert them into other records.


I need two things I do not know how to do:


1. - That when transformation runs, check the records that already exist in the target database and update only those that have changed and insert the new. But they have not changed not touch.


Two. - I have a field in the source table is VISITDATE. I need to pass as parameter the starting date and records not select records with the field VISITDATE <start date.


I created, on the tab of the transformation parameters, the startdate parameter, but as I do that by executing a transformation I ask the value of the start date and also make me VISITDATE filter <start date.


I do not know if I explained well, but thanks anyway.


Greetings to all!