truncate table with old data and load it with the latest file available

Hi All,

    I have a scenario like this.

I want to load a flat file ( for example ABC_28_05_2013.csv) to a table. In future ,I would receive new file like ABC_29_05_2013.csv. Now i have to truncate the table and load it with this new file.

  But if there is no new file , the table should not get truncated.

Note : If there is new file , old file wont get deleted. Both will be available in the server.

I am using Data services 4.2.

Many thanks in advance,

Sathish S