【www.bbyears.com--今天更新】
报错信息：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.
参考资料：
https://stackoverflow.com/questions/1836173/entity-framework-store-update-insert-or-delete-statement-affected-an-unexpec
原因：主键id未设置自增，导致插入失败。
解决方案：表的主键id设置自增。
mysql设置方式：在表上右键-->设计表-->选中主键id-->勾选即可。
sqlserver设置方式：在表上右键-->设计表-->选中主键id-->双击“(是标识)”的值，改为是，标识增量和标识种子设置为1即可。
