Constructing an SQL WHERE clause for a composite key

I just realized that I have a problem with key construction in my JDBCR4 project:

It works great when the key is a single field. But it fails when it's multiple fields.

Suppose I have a file with keyfields FOO and BAR, with FOO being a 9-digit number, and BAR being an 11-digit number.

Now, suppose I have records with the following key values in the file:

FOO BAR
180624 10000105018
180627 10000105020
180639 10000105100
180639 10000105333
180639 10000105334
180648 10000105169
180651 10000105273
180652 10000105275
180654 10000105292
180654 10000105293


Now, suppose I'm looking for two result sets, both "ORDER BY FOO, BAR": one of all the records from 180648 10000105169 through EOF, and one of all the records from TOF to 180648 10000105169.

Obviously, if I were to do "WHERE FOO <= 180648 AND BAR <= 10000105169" for the second result set, it would miss 180639 10000105333 and 180639 10000105334 entirely, skipping back to 180639 10000105100.

I *could* do something like "WHERE (FOO <= 180648 AND BAR <= 10000105169) OR FOO < 180648" -- but what happens if I'm keying on 3 fields? Is there an easier, more general solution?

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JHHL