Datatable and dataset

Question

Hello everyone, please help me....

I want to validate some isbn numbers from excel spreadsheet with my database values, currently I have more than 9000 records in my database. My approch was to grab every record from database and store it into dataset and then perform checking against each value.  I have 1800 new records from excel spreadsheet, these records need to be checked agianst my database values,  such that I should not add new entries if it alredy exist.
When I load my database record into dataset , it actually grabs only first 2888 records...

Please suggest me best  possible approch for this kind of checking, also what is max amount of records a datatable can hold at a time.....