linQ - Need to optimize slow subquery code (.contains)

[castaway]

Hi

The file database I'm using is not SqLite but *.mdb (see post#8).
When I first started this project, long time ago, I choose *.mdb instead of *.sqlite because I already had *.mdb file and stored procedures knowledge.

Sqlite has done a long way since then, and maybe I'll try also to use it sometimes !