One-step study of the series of articles on LINQ to SQL

At present, there are not many materials for writing to SQL. I am at a limited level. If there is something wrong or misleading, please point it out. Thank you.

2. One-step learning of LINQ to SQL (1): prerequisites
   
4. One-step learning of LINQ to SQL (2): datacontext and Entity
   
6. Step by step to learn about LINQ to SQL (3): add, delete, and modify
   
8. One-step learning of LINQ to SQL (4): query syntax
   
10. One-step learning of LINQ to SQL (5): Stored Procedure
    
12. One-step learning of LINQ to SQL (6): Exploring features
    
14. One-step learning of LINQ to SQL (7): concurrency and transactions
    
16. One-step learning of LINQ to SQL (8): inheritance and relationship
    
18. One-step learning of LINQ to SQL (9): Other supplements
    
20. One-step learning of LINQ to SQL (10): An Example of Layered Architecture

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Linq2sql code Daquan