https://msdn.microsoft.com/en-us/library/cc716697.aspx
In the Model Browser, right-click the .edmx file and select Update Model from Database.
The Update Model Wizard starts. If there is no database connection specified, the Choose Your Database Connection dialog box appears. Otherwise, the Choose Your Database Objects dialog box appears.
How to: Update an .edmx File when the Database Changes
原文：http://www.cnblogs.com/chucklu/p/5899111.html