求大神解答 EF的问题

[l2999019]

今天遇到一个需要在LINQ中使用SQL方法的问题..
以前一直用的SqlFunctions对象,今天却报错了..
后来有大神说可以用EntityFunctions 还是报错..
最后用DbFunctions 就好了..
求大神解答这三个对象到底是什么情况? - - 有什么区别?

[threenewbee]

不同的Provider用的桩函数不同，一个是EF一个是LINQ to SQL

[l2999019]

引用 1 楼 caozhy 的回复:

不同的Provider用的桩函数不同，一个是EF一个是LINQ to SQL

有三个啊 - - DbFunctions 呢?

[l2999019]

没人了么.

[q107770540]

SqlFunctions is a static class introduced in EF4 and is in assembly System.Data.Entity. It contains a long list of methods like Cos, DateAdd, DateDiff, DatePart, GetDate, Exp, Sign, which are mapped to SQL Server functions. These static functions can be called in LINQ to Entities queries EF4 also introduced the static EntityFunctions class. This class exposes conceptual model canonical functions which can be used in LINQ to Entities queries. These functions are mapped to the functions in the System.Data.Metadata.Edm namespace and they are only available in the conceptual model. https://msdn.microsoft.com/en-us/library/system.data.objects.sqlclient.sqlfunctions.aspx https://msdn.microsoft.com/en-us/library/system.data.objects.entityfunctions.aspx