Phil Parkin (5/7/2013)
This is probably what you meant by "I can program the loading process in another way, I know." but to remove most of the doubt I like to code extracts like this off of an ever-increasing key, i.e. an IDENTITY column setup as a unique index or primary key. This way I will select the maximum ID into a variable, then select all rows that are less than or equal to that ID.
+1 to this, me too.
Ditto on the +1. If you want to do only an incremental extraction (instead of extracting ALL rows where ID < MAX(ID), create a log table with a column called extractedThroughID or something similar. When you begin the extraction, read the most recent extractedThroughID from the log table into a variable (lastExtractEndID, for example) and the MAX(ID) into another variable (e.g., currentExtractEndID) and extract only rows WHERE ID > lastExtractStartID AND ID <= currentExtractEndID. When the extraction process completes successfully, insert the value of currentExtractEndID in the log table as extractedThroughID so the extraction will start from there next time.
Jason Wolfkill