获取linq中表的CURRENT IDENTITY值。 [英] Get CURRENT IDENTITY value of a table in linq.

问题描述

我正在使用C＃/ .NET应用程序，我需要使用LINQ获取表的当前标识值。或者我可以使用sql查询通过使用 var num = DataContext.ExecuteCommand（Select IDENT_CURRENT（'table'））; ，通过使用来完成任务这段代码，我得到的值= -1。

或

var num = DataContext.ExecuteQuery< short>（（Select IDENT_CURRENT（ 'table'））;< / short> ，通过使用此代码，我收到异常指定的强制转换无效。并且值仍为NULL。如果我做错了，请纠正我。如果有更好的方法可以执行此任务，请告诉我。



感谢您的帮助提前。

Hi,
I am working on a C#/.NET application where I need to get Current Identity value of the table using LINQ. Or else I can use the sql query to get the task done by either using var num = DataContext.ExecuteCommand("Select IDENT_CURRENT ('table')");, by using this code, i am getting the value = -1.
or
var num = DataContext.ExecuteQuery<short>(("Select IDENT_CURRENT ('table')");</short>, by using this code, I am getting an exception "Specified cast is not valid." and the value remains NULL. Correct me if I am doing something wrong. let me know if there are any better ways to do this task.

Thanks for ur help in advance.

推荐答案

你可能会这样做：

You could probably do this instead:

select MAX(id) from table

编辑=====================



我刚刚遇到了一些事情。如果你是d在当前加载的dataContext中，您的代码将无法正常工作。您必须实际查询数据库而不是数据上下文对象。当您从数据库中获取数据集时，表的系统信息都不会随之返回。您将再次使用SQLCommand，或者将存储过程中的IDENT_CURRENT作为输出变量返回并存储，以便在需要时使用。

EDIT =====================

Something just occurred to me. If you're doing this in a currently loaded dataContext, your code won't work. You have to actually query the database as opposed to your data context object. When you get a dataset back from the database, none of the table's system info comes back with it. You're going to HAVE to use SQLCommand again, or return the IDENT_CURRENT from the stored procedure as an output variable and store that for use when it's needed.

使用此：

int lastrouteid = Convert.ToInt32（routingDbContext.Database.SqlQuery< decimal>（Select IDENT_CURRENT（'Routing.RouteDescriptionTable'），new object [0]）。FirstOrDefault（））;

use this:
int lastrouteid = Convert.ToInt32(routingDbContext.Database.SqlQuery<decimal>("Select IDENT_CURRENT ('Routing.RouteDescriptionTable')", new object[0]).FirstOrDefault());

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