EF(EntityFramework) 插入或更新數據報錯

報錯信息：Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=472540 for information on understanding and handling optimistic concurrency exceptions.

參考資料：https://stackoverflow.com/questions/1836173/entity-framework-store-update-insert-or-delete-statement-affected-an-unexpec

原因：主鍵id未設置自增，導致插入失敗。

解決方案：表的主鍵id設置自增。

mysql設置方式：在表上右鍵-->設計表-->選中主鍵id-->勾選即可。

sqlserver設置方式：在表上右鍵-->設計表-->選中主鍵id-->雙擊“(是標識)”的值，改為是，標識增量和標識種子設置為1即可。