join 6個Table，QO(Query Optimizer)至少要分析720次

http://www.benjaminnevarez.com/2010/06/optimizing-join-orders/

join 3個Table，QO(Query Optimizer)至少要分析6次
join 6個Table，QO(Query Optimizer)至少要分析720次
正規化程度越高，join過多資料表容易發生查詢效能問題

https://www.udemy.com/sql-server-table-index/

TSQL和LINQ預設都是INNER JOIN

FROM (Transact-SQL)
https://docs.microsoft.com/en-us/sql/t-sql/queries/from-transact-sql

Join Operations (C#)
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/concepts/linq/join-operations