如何获得SQL Server的序列的下一个值在实体框架？ [英] How to get next value of SQL Server sequence in Entity Framework?

问题描述

我想利用SQL Server的 序对象实体框架中显示数字序列之前将其保存到数据库中。

I want to make use SQL Server sequence objects in Entity Framework to show number sequence before save it into database.

在当前情况下，我在做一个存储过程（前值存储在一个表）由增量相关的东西，并通过该值的C＃代码。

In current scenario I'm doing something related by increment by one in stored procedure (previous value stored in one table) and passing that value to C# code.

要实现这一目标，我需要一个表，但现在我想将其转换为序对象（它会给什么优势？）。

To achieve this I needed one table but now I want to convert it to a sequence object (will it give any advantage ?).

我知道如何创建序列，并获得在SQL Server下一个值。

I know how to create sequence and get next value in SQL Server.

但我想知道如何获得实体框架序列的下一个值的SQL Server 对象吗？

But I want to know how to get next value of sequence object of SQL Server in Entity Framework?

我是无法找到的相关问题在SO。

I am to unable to find useful answers in Related questions in SO.

在此先感谢。

推荐答案

您可以创建一个简单的存储程序中的SQL Server，它选择这样的一个序列值：

You can create a simple stored procedure in SQL Server that selects the next sequence value like this:

CREATE PROCEDURE dbo.GetNextSequenceValue 
AS 
BEGIN
    SELECT NEXT VALUE FOR dbo.TestSequence;
END

然后可以导入存储过程到实体框架的EDMX模型，并调用存储过程并获取这样的序列：

and then you can import that stored procedure into your EDMX model in Entity Framework, and call that stored procedure and fetch the sequence value like this:

// get your EF context
using (YourEfContext ctx = new YourEfContext())
{
    // call the stored procedure function import   
    var results = ctx.GetNextSequenceValue();

    // from the results, get the first/single value
    int? nextSequenceValue = results.Single();

    // display the value, or use it whichever way you need it
    Console.WriteLine("Next sequence value is: {0}", nextSequenceValue.Value);
}

更新：其实，你可以跳过存储程序和公正运行的EF背景下，这个原始的SQL查询：

Update: actually, you can skip the stored procedure and just run this raw SQL query from your EF context:

public partial class YourEfContext : DbContext 
{
    .... (other EF stuff) ......

    // get your EF context
    public int GetNextSequenceValue()
    {
        var rawQuery = Database.SqlQuery<int>("SELECT NEXT VALUE FOR dbo.TestSequence;");
        var task = rawQuery.SingleAsync();
        int nextVal = task.Result;

        return nextVal;
    }
}

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