Expressions And Datareader Source

Greetings my SSIS friends,

Apologies for asking a similar question again but I am still non the wiser with this problem!

Let me explain to you my situation and the method I've adopted to try and solve it.

I have some source data residing in a SQL Server 6.5 database. The source data consists of a single table. For this example I will assume that my table contains only 2 columns, an ID column called result_ID and a Result_Name.

The idea is to retrieve new data each time the package is run. We will know this because the result_IDs in the source table will be greater than the maximum result_ID in my destination table . The way the package should work is like this :

1) Retrieve maximum result_ID from destination table

2) retrieve data from source table where result_ID > maximum result_ID from destination table.



My package consists of a

1) SQL Query Task which retrieves the maximum result_ID and places it in a user variable (type Int32).

2) A Data flow task with a Datareader source adapter which uses an expression to retrieve the data. My expression looks like this : "select * from result where result_id > " + (dt_str, 10, 1252) @[User::max_result_id]

When I run my package the first time all the rows are retrieved (as my destination table is empty to begin with). BUT when I run it the second time the same thing happens again!! All rows are retrieved.

I placed a breakpoint at the point where the variable gets populated with the maximum result_ID and true enough, the variable gets populated with the correct result_ID BUT then that variable gets reset to 0 in my expression!



This problem is driving me crazy! Has anybody out there experienced this kind of problem before?! What are the ways to solve it?!

Thanks for your help in advance.