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Questions on inserting to Linq to Sql

Posted By:      Posted Date: August 31, 2010    Points: 0   Category :ASP.Net
I have a situation that I can't figure out.  Say I have tableMain, and tableSub.  Say I have an association in the dbml between tableMain and tableSub such that tableMain is the parent class and tableSub is the child class.   I can't insert any records programmatically into tableSub.  I get a "Specified cast is not valid." error.  If I remove the association and run the exact same code, the record is inserted without a problem.This has been an issue for me for some time.  I've resorted to haveing a second dbml to use when inserting records into tables with an association with my main table, but I don't like having tables in more than one dbml unless it's really necessary.  It's too easy to forget to update a dbml when changing a table structure.Does anyone know why this is happening?

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