you havent written an insert, update or delete query. Just a select query. your cmd is a "select" command it ONLY knows about getting data. You need a new command for each of the CRUD actions you intend to do (you should in theory write one for each but if you know 100% you will never need a delete then you can leave it out). So you cannot call Update on a command whos SQL is a SELECT query.

Create a new command but this time an Insert Command (with Inser INTO sql or the name of an insert stored proc or query in your database.

I would recommend you use a data adapter and fill all 4 commands in and use this to do everything you need.

If you need more explanation let me know